Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

John Gialousakis, O.D.

Optometrist in Downers Grove, IL · enumerated 2014.

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

National Provider Identifier

1184038606

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Registry record

Entity type Individual (Type 1)

Name John Gialousakis

Credential O.D.

Sex Male

Practice address 3450 Lacey Rd, Downers Grove, IL, 60515

Phone (630) 743-4500

Fax (630) 743-4537

Enumeration date Jun 12, 2014

Last updated in NPPES Jun 5, 2019

Taxonomy & licenses

152WC0802X Corneal and Contact Management Optometrist Eye and Vision Services Providers · License 046011186 (IL) Secondary

152W00000X Optometrist Eye and Vision Services Providers · License 046011186 (IL) Primary

OD · Doctor of Optometry: A licensed optometrist providing primary vision care, eye exams, and corrective lenses. About the OD 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.

Read the full guide → Validate an NPI →

Frequently asked questions

What is the NPI number for John Gialousakis?

The National Provider Identifier (NPI) for John Gialousakis is 1184038606, a Type 1 (individual) record in the CMS NPPES registry.

Where does John Gialousakis practice?

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

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Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2019-06-05.