Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Guillermo Diaz, NP-P

Psychiatric/Mental Health Nurse Practitioner in Hicksville, NY · enumerated 2016.

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

National Provider Identifier

1164975801

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Registry record

Entity type Individual (Type 1)

Name Guillermo Diaz

Credential NP-P

Sex Male

Practice address 185 W John St # 113, Hicksville, NY, 11801

Phone (646) 856-9971

Fax (516) 531-8539

Enumeration date Jul 29, 2016

Last updated in NPPES Sep 5, 2025

Taxonomy & licenses

363LP0808X Psychiatric/Mental Health Nurse Practitioner Physician Assistants & Advanced Practice Nursing Providers · License 402068 (NY) Primary

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

Where does Guillermo Diaz practice?

The practice location on file with NPPES is in Hicksville, NY. Providers can have multiple locations; NPPES lists the primary practice address.

What is the NPI number for Guillermo Diaz?

The National Provider Identifier (NPI) for Guillermo Diaz is 1164975801, a Type 1 (individual) record in the CMS NPPES registry.

Other providers at this practice address

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Norma Ramirez Psychiatric/Mental Health Nurse Practitioner · Hicksville, NY NPI 1366391922

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2025-09-05.