MARIE A HOLLENHORST MD, PHD
NPI 1497193999
Internal Medicine - Hematology in Boston, MA
About Marie A Hollenhorst Md, Phd NPPES
Official registry information on file with the National Plan and Provider Enumeration System.
MARIE A HOLLENHORST MD, PHD (NPI 1497193999) is an individual hematology provider in Boston, Massachusetts, licensed in Massachusetts (262787) and active in the NPI registry since June 2013. She is enrolled in Medicare PECOS, is affiliated with Brigham And Women's Hospital, and maintains a secondary practice location in Boston.
NPPES Registry Identity
Specialties & Licenses 2
Secondary Practice Location 1
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
Marie A Hollenhorst Md, Phd 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.
Medicare Billing Reassignments
4Medicare enrollment records show Marie Hollenhorst reassigns Medicare billing to 4 organizations. Each organization bills Medicare for the services this provider delivers there; the nearest is listed first.
Boston, MA 02115
- Reassigned Medicare billing, Massachusetts enrollment
- 4,574 clinicians in this Medicare group
Boston, MA 02215
- Reassigned Medicare billing, Massachusetts enrollment
- 1,026 clinicians in this Medicare group
Boston, MA 02114
- Reassigned Medicare billing, Massachusetts enrollment
- 6,234 clinicians in this Medicare group
Boston, MA 02114
- Reassigned Medicare billing, Massachusetts enrollment
- 6,360 clinicians in this Medicare group
Source: CMS Revalidation Reassignment List, October 2026 release. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.
Hospital Affiliations CMS Care Compare
Hospitals where this provider delivers care, identified from recent Medicare claims and place-of-service records.
Brigham And Women's Hospital
Acute Care Hospitals · Boston, MAPhysician Visit Costs CMS claims · ZIP area
Typical Medicare office-visit costs in the 02115 ZIP code area, from fee-for-service claims. These are area statistics, not this provider’s prices; actual charges vary by service and coverage.
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.
BOSTON, MA 02115
BOSTON, MA 02115
BOSTON, MA 02115
BOSTON, MA 02115
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 Marie Hollenhorst's NPI number?
The NPI number for Marie Hollenhorst is 1497193999. It was assigned to this individual provider in the NPPES registry on June 6, 2013.
Where is Marie Hollenhorst located?
Marie Hollenhorst practices at 75 Francis St, Boston, MA 02115. The listed phone number is (617) 732-5500.
What is Marie Hollenhorst's specialty?
The primary specialty registered for this NPI is Internal Medicine, specializing in Hematology, with taxonomy code 207RH0000X.
Is Marie Hollenhorst enrolled in Medicare?
Yes. Marie Hollenhorst 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 Marie Hollenhorst's services?
According to the CMS Revalidation Reassignment List (October 2026 release), Marie Hollenhorst reassigns Medicare benefits to 4 organizations: Brigham & Womens Physicians Organization Inc (Boston, MA), Dana-Farber Cancer Institute, Inc. (Boston, MA), The General Hospital Corporation (Boston, MA) and Massachusetts General Physicians Organization Inc (Boston, MA). 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 Marie Hollenhorst's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.
Is Marie Hollenhorst affiliated with any hospitals?
According to CMS data, Marie Hollenhorst is affiliated with Brigham And Women's Hospital.
When was this NPI record last updated?
The NPPES record for Marie Hollenhorst was last updated on February 11, 2026. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 8 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.
# Marie A Hollenhorst, MD, PHD · NPI 1497193999
Hematology physician in Boston, Massachusetts. Individual provider, active in the CMS NPPES registry since June 6, 2013.
## Identity
- **NPI:** 1497193999 (Entity type: Individual)
- **Enumerated:** June 6, 2013
- **Primary specialty:** Internal Medicine - Hematology · taxonomy 207RH0000X
- **State license:** 262787 (Massachusetts)
- **Sole proprietor:** No
## Practice location
- **Address:** 75 FRANCIS ST, Boston, MA 02115-6110
- **Phone:** (617) 732-5500
## Medicare
- **Medicare:** Enrolled (PECOS); accepts Medicare assignment
- **Ordering & referring:** eligible for Part B labs & imaging, durable medical equipment, home health, power mobility devices
- **Bills Medicare through:** 4 organizations under Medicare reassignment (form CMS-855R): Brigham & Womens Physicians Organization Inc (NPI 1033535497, Boston, MA); Dana-Farber Cancer Institute, Inc. (NPI 1851333686, Boston, MA); The General Hospital Corporation (NPI 1023049236, Boston, MA); Massachusetts General Physicians Organization Inc (NPI 1801874573, Boston, MA) · CMS Revalidation Reassignment List, October 2026 release
- **Medical school:** Harvard Medical School, class of 2013
## Record status
- **NPPES last updated:** February 11, 2026
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Source: [NPI Profile](https://npiprofile.com/npi/1497193999) · Data from the CMS NPPES public registry.