Dr. Mark A Cassellius, D.C.
Dr. Mark A Cassellius is a Chiropractor provider (Chiropractor) practicing in Onalaska, WI, registered in the NPPES registry with NPI 1669433462 since 2006. The credential DC stands for Doctor of Chiropractic. Practices at Active Chiropractic Clinic LLC (listed at the same practice address in NPPES).
✓ Active NPI ✓ Valid NPI checksum Sole proprietor
| NPI | 1669433462 |
|---|---|
| Entity type | Individual (Type 1) |
| Name | Dr. Mark A Cassellius |
| Credential | D.C. |
| Sex | Male |
| Practice address | Onalaska, WI, 54650 |
| Phone | 6087833307 |
| Fax | 6087799728 |
| Enumeration date | 2006-03-31 |
| Last updated in NPPES | 2011-04-26 |
Street address withheld — NPPES sole-proprietor addresses can be home addresses. See our data policy.
Taxonomy & licenses
| Taxonomy code | Specialty | Primary | License | State |
|---|---|---|---|---|
| 111N00000X | Chiropractor | Primary | 2293 | WI |
DC — Doctor of Chiropractic: A licensed chiropractor focusing on musculoskeletal and nervous system disorders. About the DC credential
Other identifiers
| Identifier | Type | State | Issuer |
|---|---|---|---|
| 38800700 | Medicaid | WI | — |
| 350016946 | Other | WI | RR MEDICARE # |
Copy-ready billing details
Provider: Mark Cassellius, D.C. NPI: 1669433462 Taxonomy: 111N00000X (Chiropractor) Address: Onalaska, WI, 54650
Other providers at this practice address
| NPI | Name | Type | Specialty | Location |
|---|---|---|---|---|
| 1326354077 | Active Chiropractic Clinic LLC | Organization | Chiropractor | Onalaska, WI |
| 1205181310 | Carolyn Seraukas | Individual | Massage Therapist | Onalaska, WI |
| 1720544620 | Brennan Quinn | Individual | Acupuncturist | Onalaska, WI |
Verify this record
Cross-check NPI 1669433462 against the authoritative CMS record: view Dr. Mark A Cassellius on the official NPPES registry .
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 or validate an NPI number.
Frequently asked questions
What is the NPI number for Mark Cassellius?
Where does Mark Cassellius practice?
Source: CMS NPPES (public data). Snapshot 2026-07-11. Provider record last updated 2011-04-26.