Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum Sole proprietor

Dr. Mark Allen Stein, M.D.

Diagnostic Radiology Physician in Santa Monica, CA · enumerated 2014 · practices at Acology Home Healthcare, Inc.

Data current as of Jul 13, 2026 · sourced from CMS NPPES

National Provider Identifier

1346644887

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Registry record

Entity type Individual (Type 1)

Name Dr. Mark Allen Stein

Credential M.D.

Sex Male

Practice address Santa Monica, CA, 90403

Phone (310) 828-9640

Fax (206) 202-5620

Enumeration date Oct 13, 2014

Last updated in NPPES Oct 13, 2014

Street address withheld: NPPES sole-proprietor addresses can be home addresses. See our data policy.

Taxonomy & licenses

2085R0202X Diagnostic Radiology Physician Allopathic & Osteopathic Physicians · License A23799 (CA) Primary

MD · Doctor of Medicine: A physician who completed medical school (allopathic medicine), residency training, and state licensure. About the MD credential

What is an NPI number?

A National Provider Identifier (NPI) is a unique 10-digit number that CMS assigns to every U.S. healthcare provider and organization under HIPAA. Type 1 NPIs identify individual providers; Type 2 NPIs identify organizations. The NPI appears on insurance claims, prescriptions, and credentialing paperwork, and never changes, even if the provider moves or changes specialty.

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Frequently asked questions

Is this the official NPI registry?

No. NPI Portal is a private site built on public CMS NPPES data. The official registry is npiregistry.cms.hhs.gov, operated by CMS.

What specialty is Mark Stein?

Mark Stein is registered in NPPES with the primary taxonomy of Diagnostic Radiology Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

Other providers at this practice address

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Acology Home Healthcare, Inc Durable Medical Equipment & Medical Supplies · Santa Monica, CA NPI 1215007364

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2014-10-13.