Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of August 10, 2026.

Frederick E. Siefert, MD, PC

Organization Internal Medicine Physician · NPI 1417093683

Frederick E. Siefert, MD, PC is an Internal Medicine Physician in Old Greenwich, Connecticut. Licensed in Connecticut. Registered with an NPI since 2007.

Licensed in
CT
In the registry since
2007
What do these letters mean?
PC — Professional corporation
A form of business registration, not a clinical qualification.

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Practice location Address checks out

8 W End Ave
Old Greenwich, CT 06870-1642
Phone: (203) 637-5406
Fax: (203) 637-5408
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Internal Medicine Physician (primary) Taxonomy 207R00000X (CT)

Record details

NPI number1417093683
Entity typeOrganization (Type 2)
Organization subpartNo
Authorized official Frederick Siefert — President · (203) 637-5406
NPI enumeratedJanuary 29, 2007
Last updated in NPPESSeptember 10, 2007
Mailing address8 W End Ave, Old Greenwich, CT 06870-1642

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