Type 1 · Individual ✓ Active NPI ✓ Valid NPI checksum

Dr. William D. Cox Jr., M.D.

Sports Medicine (Orthopaedic Surgery) Physician in Crystal Lake, IL · enumerated 2006.

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

National Provider Identifier

1407928062

Verified

See something wrong? Report a correction

Registry record

Entity type Individual (Type 1)

Name Dr. William D. Cox Jr.

Credential M.D.

Sex Male

Practice address 420 N Il Route 31, Crystal Lake, IL, 60012

Phone (815) 356-5200

Fax (815) 356-5262

Enumeration date Nov 15, 2006

Last updated in NPPES Oct 19, 2018

Taxonomy & licenses

207X00000X Orthopaedic Surgery Physician Allopathic & Osteopathic Physicians · License 036080933 (IL) Secondary

207XX0005X Sports Medicine (Orthopaedic Surgery) Physician Allopathic & Osteopathic Physicians · License 036080933 (IL) Primary

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

Other identifiers

Identifier	Type	State	Issuer
036080933	Other	IL	STATE LICENSE
036080933	Medicaid	IL	-

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 specialty is William Cox?

William Cox is registered in NPPES with the primary taxonomy of Sports Medicine (Orthopaedic Surgery) Physician. The taxonomy code describes the provider's classification and area of specialization for claims and credentialing.

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.

Other providers at this practice address

Browse all →

Source: CMS NPPES (public data). Snapshot 2026-07-13. Provider record last updated 2018-10-19.