1. Home
  2. Directory
  3. Wisconsin
  4. Weston
  5. Hospitalist
  6. NPI Profile

DR. GREGORY WAYNE GRZESIK D.O.
NPI 1316389372
Hospitalist in Weston, WI

Active since July 18, 2013PECOS EnrolledAccepts Medicare Assignment
84.56/100
CMS Quality Rating
3400 MINISTRY PKWY, WESTON, WI 54476(715) 393-1220 Get Directions Write a Review

NPPES record last updated: June 18, 2025. Verified against the NPPES registry weekly; last sync: October 25, 2026.

Record update history: Jun 18, 2025, Dec 30, 2024, Aug 23, 2016 (3 updates tracked since 2016).

About Dr. Gregory Wayne Grzesik D.o. NPPES

Official registry information on file with the National Plan and Provider Enumeration System.

DR. GREGORY WAYNE GRZESIK D.O. (NPI 1316389372) is an individual hospitalist provider in Weston, Wisconsin, licensed in Wisconsin (65797) and active in the NPI registry since July 2013. He is enrolled in Medicare PECOS, is affiliated with Marshfield Medical Center, and maintains a secondary practice location in Rhinelander.

NPPES Registry Identity

NPI1316389372
Entity TypeIndividualMale
Primary Taxonomy208M00000X
Provider Legal NameDR. GREGORY WAYNE GRZESIKCredential: D.O.
Location Address3400 MINISTRY PKWYWeston, WI 54476-5220
Mailing Address1000 N Oak AveMarshfield, WI 54449-5702 · (715) 387-5511
Phone(715) 393-1220
Sole ProprietorNo
Medical School CMSLake Erie College Of Osteopathic Medicine, ErieGraduated 2013
Enumeration DateJuly 18, 2013
Last NPPES UpdateJune 18, 20253 updates tracked since enumeration
NPPES CertifiedJune 18, 2025
✔ NPI 1316389372 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses 2

★ Primary SpecialtyHospitalistAllopathic & Osteopathic Physicians
Taxonomy Code208M00000X
License✔ Licensed in WI · 65797
Definition
Hospitalists are physicians whose primary professional focus is the general medical care of hospitalized patients. Their activities include patient care, teaching, research, and leadership related to Hospital Medicine. The term 'hospitalist' refers to physicians whose practice emphasizes providing care for hospitalized patients.
Also ListedInternal MedicineTaxonomy 207R00000X · License 65797-21 (WI), 125-062888 (IL)
3400 MINISTRY PKWY, Weston, WI 54476
Open in Google Maps ↗

Secondary Practice Location 1

Location 12251 N Shore DrRhinelander, WI 54501-6710 · Phone (715) 361-4700

Medicare Participation & PECOS CMS

Medicare enrollment, assignment, billing reassignment, and ordering and referring status from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare and accepts Medicare assignment

Dr. Gregory Wayne Grzesik D.o. is registered in PECOS and agrees to accept the Medicare-approved amount as full payment. Medicare patients are not billed beyond the standard deductible and coinsurance.

PECOS PAC ID2961706643
PECOS Enrollment IDI20160705002027
Eligible to Order & Refer✔ Part B Labs & Imaging✔ Durable Medical Equipment✔ Home Health Agency– Power Mobility DevicesPer the CMS Ordering and Referring file. Eligibility means Medicare pays claims that this provider orders or refers for these categories.

Medicare Billing Reassignments

6

Medicare enrollment records show Gregory Grzesik reassigns Medicare billing to 6 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.

Mchs Hospitals Inc
Same address
Clinic/Center
3400 MINISTRY PKWY
Weston, WI 54476
  • Reassigned Medicare billing, Wisconsin enrollment
  • Also billed through NPI 1952890873 (Wisconsin)
  • 2,476 clinicians in this Medicare group
NPI 1992336655 (715) 393-1000
Marshfield Clinic Inc
34 mi
Clinic/Center
1000 N OAK AVE
Marshfield, WI 54449
  • Reassigned Medicare billing, Wisconsin enrollment
  • 2,540 clinicians in this Medicare group
NPI 1952347981 (715) 387-5511
Memorial Hospital, Inc
56 mi
Clinical Medical Laboratory
216 SUNSET PL, MEMORIAL HOSPITAL, INC
Neillsville, WI 54456
  • Reassigned Medicare billing, Wisconsin enrollment
  • Also billed through NPI 1346239373 (Wisconsin)
  • 1,283 clinicians in this Medicare group
NPI 1679746747 (715) 743-3101
Flambeau Hospital Inc
83 mi
Clinic/Center
98 SHERRY AVE
Park Falls, WI 54552
  • Reassigned Medicare billing, Wisconsin enrollment
  • Also billed through NPI 1700963048 (Wisconsin)
  • 1,351 clinicians in this Medicare group
NPI 1194317966 (715) 762-2484
Beaver Dam Community Hospitals Inc
96 mi
Family Medicine
180 GATEWAY DR
Waupun, WI 53963
  • Reassigned Medicare billing, Wisconsin enrollment
  • 1,447 clinicians in this Medicare group
NPI 1629374780 (920) 345-1306
Lakeview Medical Center Inc Of Rice Lake
105 mi
Clinic/Center
806 2ND ST
Chetek, WI 54728
  • Reassigned Medicare billing, Wisconsin enrollment
  • 1,616 clinicians in this Medicare group
NPI 1659008605 (715) 924-2000

Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Areas of Expertise CMS Part B claims 3

Services this provider delivered to Medicare fee-for-service patients, from the CMS Medicare utilization data. Higher counts generally reflect more experience with a service; care delivered outside Medicare is not included.

Subsequent hospital care with moderate levelof medical decision making, if using time, at least 35 minutes 99232
Follow-up hospital inpatient care involves daily check-ups while you're admitted in the hospital. Typically, a healthcare provider spends about 25 minutes each day reviewing your condition, adjusting treatment if needed, and answering any questions you might have.
134 services52 patients
Hospital discharge day management, more than 30 minutes 99239
Hospital discharge day management over 30 minutes involves a detailed process to ensure a smooth transition from hospital to home. It includes final examinations, discussion of your hospital stay, post-discharge instructions, and coordinating follow-up care.
36 services34 patients
Initial hospital care with straightforward or low-level medical decision making, if using time, at least 55 minutes 99222
Initial hospital inpatient care is a service where a healthcare provider spends about 50 minutes per day overseeing your care while you're admitted in the hospital. This includes reviewing your health status, planning your treatment, and ensuring your safety and comfort.
20 services20 patients

Hospital Affiliations CMS Care Compare 3

Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.

Marshfield Medical Center

Acute Care Hospitals · Marshfield, WI
3/5 CMS rating
OwnershipVoluntary non-profit - Church
CMS Certification Number520037
Location611 St Joseph AveMarshfield, WI 54449 · Wood County
Emergency services Birthing friendly

Marshfield Medical Center - Weston

Acute Care Hospitals · Weston, WI
3/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number520202
Location3400 Ministry ParkwayWeston, WI 54476 · Marathon County
Emergency services Birthing friendly

Marshfield Medical Center - Minocqua

Acute Care Hospitals · Minocqua, WI
2/5 CMS rating
OwnershipVoluntary non-profit - Private
CMS Certification Number520212
Location9576 Highway 70Minocqua, WI 54548 · Oneida County
Emergency services Birthing friendly

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 54476 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.

New Patient
$123.69 typical visit price
range $53.90 – $163.24
Typical copayment $30.92 (range $13.47 – $40.81)
Most-billed visit code 99204
Established Patient
$95.41 typical visit price
range $17.40 – $133.76
Typical copayment $23.85 (range $4.35 – $33.44)
Most-billed visit code 99214
Amounts reflect what Medicare beneficiaries in this ZIP area are typically charged for office visits. Patients with other coverage should check their individual plans.

Medicare Quality Performance CMS QPP · MIPS

Performance in the CMS Quality Payment Program: the MIPS final score across four weighted categories, and the individual quality measures reported to Medicare.

84.56/100
MIPS Final ScoreMerit-based Incentive Payment System · CMS Quality Payment Program
Scored as part of a group practice
Quality89.8
Promoting Interoperability100
Improvement Activities40
Cost58.73

Other Providers at the Same Location NPPES 20

Providers registered at the same practice address, or within the immediate area, according to the NPPES registry.

DR. ANA MARIA PAGAN CABRERA M.D.
Obstetrics & Gynecology
3400 MINISTRY PKWY
WESTON, WI 54476
Marathon County (715) 393-1000
DR. KSHAMATA SHALINI MD
Internal Medicine
3400 MINISTRY PKWY
WESTON, WI 54476
Marathon County (715) 393-3000
WINFRED M KIAMAH MD
Internal Medicine
3400 MINISTRY PKWY
WESTON, WI 54476
Marathon County (715) 393-1000
DR. ALISON ROSE MARCINIAK M.D.
Emergency Medicine
3400 MINISTRY PKWY
WESTON, WI 54476
Marathon County (715) 393-3000
TINA K SCHULTZ APNP
Nurse Practitioner
3400 MINISTRY PKWY
WESTON, WI 54476
Marathon County (715) 393-3000
WARREN R. DUNN MD
Orthopaedic Surgery
3400 MINISTRY PKWY
WESTON, WI 54476
Marathon County (715) 847-3542
MS. ANN E HARMON CRNA
Nurse Anesthetist, Certified Registered
3400 MINISTRY PKWY
WESTON, WI 54476
Marathon County (715) 393-3000
JOHN H. BRAXTON M.D.
Thoracic Surgery (Cardiothoracic Vascular Surgery)
3400 MINISTRY PKWY
WESTON, WI 54476
Marathon County (715) 393-1000

Frequently Asked Questions NPPES & CMS

Common questions about this NPI record, answered from the official NPPES registry and CMS datasets shown on this page.

What is Gregory Grzesik's NPI number?

The NPI number for Gregory Grzesik is 1316389372. It was assigned to this individual provider in the NPPES registry on July 18, 2013.

Where is Gregory Grzesik located?

Gregory Grzesik practices at 3400 Ministry Pkwy, Weston, WI 54476. The listed phone number is (715) 393-1220.

What is Gregory Grzesik's specialty?

The primary specialty registered for this NPI is Hospitalist with taxonomy code 208M00000X.

Is Gregory Grzesik enrolled in Medicare?

Yes. Gregory Grzesik is registered in the Medicare PECOS system and accepts Medicare assignment, which means accepting the Medicare-approved amount as payment in full for covered services.

Which organizations bill Medicare for Gregory Grzesik's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Gregory Grzesik reassigns Medicare benefits to 6 organizations: Mchs Hospitals Inc (Weston, WI), Marshfield Clinic Inc (Marshfield, WI), Memorial Hospital, Inc (Neillsville, WI), Flambeau Hospital Inc (Park Falls, WI), Beaver Dam Community Hospitals Inc (Waupun, WI) and 1 more organization, listed in the Medicare section above. Each reassignment is filed with Medicare on form CMS-855R, signed by both the clinician and the organization, and lets the organization bill Medicare and receive payment for Gregory Grzesik's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

Is Gregory Grzesik affiliated with any hospitals?

According to CMS data, Gregory Grzesik is affiliated with Marshfield Medical Center, Marshfield Medical Center - Weston and Marshfield Medical Center - Minocqua.

When was this NPI record last updated?

The NPPES record for Gregory Grzesik was last updated on June 18, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 16 months ago. If this record has changed at CMS more recently, you can request an on-demand re-check against the live CMS registry, directly from this page.