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DR. AILEEN GRACE GUILLEN MD
NPI 1427753946
Emergency Medicine in Torrance, CA

Active since April 03, 2023PECOS Enrolled
1000 W CARSON ST BLDG N-14, TORRANCE, CA 90502(424) 306-5400 Get Directions Write a Review

NPPES record last updated: September 4, 2025. Verified against the NPPES registry weekly; last sync: October 18, 2026.

Record update history: Sep 4, 2025, Apr 3, 2023 (2 updates tracked since 2023).

About Dr. Aileen Grace Guillen Md NPPES

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

DR. AILEEN GRACE GUILLEN MD (NPI 1427753946) is an individual emergency medicine provider in Torrance, California, licensed in California (200783) and active in the NPI registry since April 2023. She is enrolled in Medicare PECOS and is a graduate of Other (2023).

NPPES Registry Identity

NPI1427753946
Entity TypeIndividualFemale
Primary Taxonomy207P00000X
Provider Legal NameDR. AILEEN GRACE GUILLENCredential: MD
Location Address1000 W CARSON ST BLDG N-14Torrance, CA 90502-2004
Mailing Address1000 W Carson StTorrance, CA 90502-2059 · (424) 306-5400
Phone(424) 306-5400
Sole ProprietorYes
Medical School CMSOtherGraduated 2023
Enumeration DateApril 3, 2023
Last NPPES UpdateSeptember 4, 20252 updates tracked since enumeration
NPPES CertifiedSeptember 4, 2025
✔ NPI 1427753946 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyEmergency MedicineAllopathic & Osteopathic Physicians
Taxonomy Code207P00000X
License✔ Licensed in CA · 200783
Definition
An emergency physician focuses on the immediate decision making and action necessary to prevent death or any further disability both in the pre-hospital setting by directing emergency medical technicians and in the emergency department. The emergency physician provides immediate recognition, evaluation, care, stabilization and disposition of a generally diversified population of adult and pediatric patients in response to acute illness and injury.
1000 W CARSON ST BLDG N-14, Torrance, CA 90502
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Group Practice 1

Group TaxonomyThis provdier is a business group of one or more individual practitioners, all of who practice with the same area of specialization.193400000X SINGLE SPECIALTY GROUP

Medicare Participation & PECOS CMS

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

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Dr. Aileen Grace Guillen Md is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

PECOS PAC ID8224528344
PECOS Enrollment IDI20251106004617
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 Reassignment

Medicare enrollment records show Aileen Guillen reassigns Medicare billing to 1 organization. The organization bills Medicare for the services this provider delivers there.

County Of Los Angeles
Same address
General Acute Care Hospital
1000 W CARSON ST # 2
Torrance, CA 90502
  • Reassigned Medicare billing, California enrollment
  • 1,939 clinicians in this Medicare group
NPI 1851363188 (310) 222-2171

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

Physician Visit Costs CMS claims · ZIP area

Typical Medicare office-visit costs in the 90502 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
$96.36 typical visit price
range $62.96 – $187.60
Typical copayment $24.09 (range $15.74 – $46.90)
Most-billed visit code 99203
Established Patient
$109.96 typical visit price
range $20.84 – $153.61
Typical copayment $27.49 (range $5.21 – $38.40)
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.

Other Providers at the Same Location NPPES 2

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

ERIKA HOLLYWOOD DO
Emergency Medicine
1000 W CARSON ST BLDG N-14
TORRANCE, CA 90502
Los Angeles County (424) 306-5400
DEVIKA NADKARNI MD
Emergency Medicine
1000 W CARSON ST BLDG N-14
TORRANCE, CA 90502
Los Angeles County (424) 306-5400

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 Aileen Guillen's NPI number?

The NPI number for Aileen Guillen is 1427753946. It was assigned to this individual provider in the NPPES registry on April 3, 2023.

Where is Aileen Guillen located?

Aileen Guillen practices at 1000 W Carson St Bldg N-14, Torrance, CA 90502. The listed phone number is (424) 306-5400.

What is Aileen Guillen's specialty?

The primary specialty registered for this NPI is Emergency Medicine with taxonomy code 207P00000X.

Is Aileen Guillen enrolled in Medicare?

Yes. Aileen Guillen is registered in the Medicare PECOS enrollment system.

Which organization bills Medicare for Aileen Guillen's services?

According to the CMS Revalidation Reassignment List (October 2026 release), Aileen Guillen reassigns Medicare benefits to County Of Los Angeles (Torrance, CA). The 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 Aileen Guillen's services. Reassignment records can lag staffing changes; confirm current arrangements with the organization.

When was this NPI record last updated?

The NPPES record for Aileen Guillen was last updated on September 4, 2025. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 13 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.