MARY CHEN MD INC
NPI 1366591174
Internal Medicine in Walnut, CA

Q: What is Mary Chen MD Inc's NPI number?

The NPI number for Mary Chen MD Inc is 1366591174. It was assigned to this organization in the NPPES registry on January 10, 2007.

Q: What is Mary Chen MD Inc's specialty?

The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.

Q: When was this NPI record last updated?

The NPPES record for Mary Chen MD Inc was last updated on April 23, 2020. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 6 years 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.

Active since January 10, 2007CLIA 05D1059051 · Waiver

18780 AMAR RD, SUITE 107, WALNUT, CA 91789(626) 810-6777(626) 810-6687 Get Directions Write a Review

NPPES record last updated: April 23, 2020. Verified against the NPPES registry weekly; last sync: October 18, 2026.

On this page

About Mary Chen Md Inc NPPES

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

MARY CHEN MD INC (NPI 1366591174) is a healthcare organization registered as an internal medicine in Walnut, California and active in the NPI registry since January 2007. The organization holds a CLIA Waiver certificate valid through September 19, 2028 and lists Mary Chen, President, as its authorized official.

NPPES Registry Identity

NPI1366591174

Entity TypeOrganization

Primary Taxonomy207R00000X

Legal Business NameMARY CHEN MD INC

Location Address18780 AMAR RD, SUITE 107Walnut, CA 91789-4560

Mailing Address18780 Amar Rd, Suite 107Walnut, CA 91789-4560 · (626) 810-6777

Phone(626) 810-6777

Fax(626) 810-6687

Organization SubpartNo

Authorized OfficialMary ChenPresident · (626) 810-6777

Enumeration DateJanuary 10, 2007

Last NPPES UpdateApril 23, 2020

NPPES CertifiedApril 23, 2020

✔ NPI 1366591174 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses

★ Primary SpecialtyInternal MedicineAllopathic & Osteopathic Physicians

Taxonomy Code207R00000X

License✔ Licensed in CA · A78207

Definition

A physician who provides long-term, comprehensive care in the office and the hospital, managing both common and complex illness of adolescents, adults and the elderly. Internists are trained in the diagnosis and treatment of cancer, infections and diseases affecting the heart, blood, kidneys, joints and digestive, respiratory and vascular systems. They are also trained in the essentials of primary care internal medicine, which incorporates an understanding of disease prevention, wellness, substance abuse, mental health and effective treatment of common problems of the eyes, ears, skin, nervous system and reproductive organs.

18780 AMAR RD, Walnut, CA 91789

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Other Identifiers 1

Medicaid00A782070CA

Group Practice 1

Group TaxonomyThis provider is a business group of one or more individual practitioners, who practice with different areas of specialization.193200000X MULTI-SPECIALTY GROUP

Medicare Participation & PECOS CMS

Medicare enrollment and the clinicians who bill Medicare through this organization, from CMS.

Medicare Enrollment Status

✔

Enrolled in Medicare (PECOS)

Mary Chen Md Inc is registered in the CMS Provider Enrollment, Chain and Ownership System (PECOS).

Clinicians Billing Medicare Through This Organization

Medicare enrollment records show 1 clinician reassigns Medicare billing to Mary Chen MD Inc, which bills Medicare for the services this clinician delivers.

Clinician (1)

Mary Chen, M.D.

Internal Medicine

NPI 1568445229

18780 AMAR RD SUITE 107
Walnut, CA 91789

(626) 810-6777

✔ PECOS✔ Accepts MedicareSame address

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

CLIA Laboratory Certificates CMS CLIA

Laboratory certificates issued under the Clinical Laboratory Improvement Amendments (CLIA) program, which sets federal quality standards for human laboratory testing in the United States. There is no official CMS crosswalk between CLIA and NPI numbers; these certificates are associated with this NPI by matching facility names, locations and phone numbers in the CMS CLIA registry.

Certificate of Waiver 05D1059051

Mary Chen, MD Inc · Walnut, CA

Active · expires Sep 19, 2028

CLIA Number05D1059051

Laboratory TypePhysician Office

Certificate Effective DateSeptember 20, 2026

Certificate Expiration DateSeptember 19, 2028

Laboratory DirectorMary Chen, MD

Laboratory Phone(626) 810-6777

Laboratory LocationMary Chen, MD Inc18780 Amar Road, Suite 107, Walnut, CA 91789

CLIA data matches this NPI record on: Address Name Phone

This certificate is issued to a laboratory to perform only waived tests.

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 Mary Chen MD Inc's NPI number?

The NPI number for Mary Chen MD Inc is 1366591174. It was assigned to this organization in the NPPES registry on January 10, 2007.

Where is Mary Chen MD Inc located?

Mary Chen MD Inc is located at 18780 Amar Rd Suite 107, Walnut, CA 91789. The listed phone number is (626) 810-6777.

What is Mary Chen MD Inc's specialty?

The primary specialty registered for this NPI is Internal Medicine with taxonomy code 207R00000X.

Is Mary Chen MD Inc enrolled in Medicare?

Yes. Mary Chen MD Inc is registered in the Medicare PECOS enrollment system.

How many clinicians bill Medicare through Mary Chen MD Inc?

According to the CMS Revalidation Reassignment List (October 2026 release), 1 clinician (Internal Medicine) reassigns their Medicare billing to Mary Chen MD Inc. A 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 the clinician's services. Reassignment records can lag staffing changes; confirm a current affiliation with the organization.

Does Mary Chen MD Inc hold a CLIA laboratory certificate?

Yes. A Certificate of Waiver (number 05D1059051) is associated with this NPI, valid through September 19, 2028. CLIA certificates authorize laboratory testing under the federal Clinical Laboratory Improvement Amendments program.

When was this NPI record last updated?

The NPPES record for Mary Chen MD Inc was last updated on April 23, 2020. NPI Profile syncs weekly with the NPPES registry data releases published by CMS. This NPI record was last updated 6 years 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.