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SEBASTIAN NIEZEN
NPI 1265162291
Internal Medicine - Gastroenterology in Boston, MA

Active since June 13, 2022
330 BROOKLINE AVE, BOSTON, MA 02215(617) 480-3735 Get Directions Write a Review

NPPES record last updated: June 30, 2025. Verified against the NPPES registry weekly; last sync: August 02, 2026.

About Sebastian Niezen NPPES

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

SEBASTIAN NIEZEN (NPI 1265162291) is an individual gastroenterology provider in Boston, Massachusetts, licensed in Massachusetts (3018049) and active in the NPI registry since June 2022.

NPPES Registry Identity

NPI1265162291
Entity TypeIndividualMale
Primary Taxonomy207RG0100X
Provider Legal NameSEBASTIAN NIEZEN
Location Address330 BROOKLINE AVEBoston, MA 02215-5400
Mailing Address330 Brookline AveBoston, MA 02215-5400 · (617) 480-3735
Phone(617) 480-3735
Sole ProprietorYes
Enumeration DateJune 13, 2022
Last NPPES UpdateJune 30, 2025
NPPES CertifiedJune 30, 2025
✔ NPI 1265162291 is a valid, active identifier and passes the ISO check-digit test.

Specialties & Licenses 2

★ Primary SpecialtyInternal Medicine · GastroenterologyAllopathic & Osteopathic Physicians
Taxonomy Code207RG0100X
License✔ Licensed in MA · 3018049
Definition
An internist who specializes in diagnosis and treatment of diseases of the digestive organs including the stomach, bowels, liver and gallbladder. This specialist treats conditions such as abdominal pain, ulcers, diarrhea, cancer and jaundice and performs complex diagnostic and therapeutic procedures using endoscopes to visualize internal organs.
Also ListedInternal MedicineTaxonomy 207R00000X · License MT226639 (PA)
330 BROOKLINE AVE, Boston, MA 02215
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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.

BETH ISRAEL DEACONESS MEDICAL CENTER
Chronic Disease Hospital (Children)
330 BROOKLINE AVE
BOSTON, MA 02215
Suffolk County (617) 677-4042
DR. BRIAN DANIEL HOBBS MD, MMSC
Internal Medicine
330 BROOKLINE AVE, PULMONARY AND CRITICAL CARE DEPARTMENT
BOSTON, MA 02215
Suffolk County (617) 667-5864
ERICA DOMMASCH MD
Dermatology
330 BROOKLINE AVE, SHAPIRO 2
BOSTON, MA 02215
Suffolk County (617) 667-3753
VAHID KIARAD M.D
Anesthesiology
330 BROOKLINE AVE
BOSTON, MA 02215
Suffolk County (617) 667-7000
DR. JONATHAN DAVID THOMAS MD
Internal Medicine (Hematology)
330 BROOKLINE AVE
BOSTON, MA 02215
Suffolk County (617) 667-7000
JULIA MARIE BERG MD
Internal Medicine
330 BROOKLINE AVE
BOSTON, MA 02215
Suffolk County (617) 667-7000
DR. MICHAEL R GOLDSTEIN PHD
Psychologist (Clinical)
330 BROOKLINE AVE
BOSTON, MA 02215
Suffolk County (617) 356-7246
SARA MURDOCK CAHILL MD
Hospitalist
330 BROOKLINE AVE
BOSTON, MA 02215
Suffolk County (617) 667-7000

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 Sebastian Niezen's NPI number?

The NPI number for Sebastian Niezen is 1265162291. It was assigned to this individual provider in the NPPES registry on June 13, 2022.

Where is Sebastian Niezen located?

Sebastian Niezen practices at 330 Brookline Ave, Boston, MA 02215. The listed phone number is (617) 480-3735.

What is Sebastian Niezen's specialty?

The primary specialty registered for this NPI is Internal Medicine, specializing in Gastroenterology, with taxonomy code 207RG0100X.

When was this NPI record last updated?

The NPPES record for Sebastian Niezen was last updated on June 30, 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.