Quick answers
- Where does Mark S. Wallis see patients?
- Medicare's clinician data lists 2 practice locations, including Marshall, TX and Longview, TX. Call before your visit to confirm the address.
- What is Mark S. Wallis's specialty?
- Medicare lists Dermatology as the primary specialty.
- Does Mark S. Wallis accept Medicare assignment?
- Yes. Medicare's clinician data says Mark S. Wallis accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- What is the phone number for Mark S. Wallis?
- (903) 503-7330, as listed in official Medicare / NPI Registry data.
- What is Mark S. Wallis's NPI number?
- 1861489049. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Practice locations
Addresses where Mark S. Wallis is enrolled with Medicare (CMS data updated 2026-10-02).
- 1900 S Washington Ave, Suite EMarshall, TX 75670 (903) 503‑7330
- 3535 N 4th St, Suite 400Longview, TX 75605 (903) 757‑3881
Group practices
Medicare enrollment lists Mark S. Wallis as a member of this group (CMS data updated 2026-10-02).
- Wallis Dermatology Associates PLLC12 clinicians in the group
Specialties
- Dermatologyprimary
Other dermatologists in Marshall
Clinicians with the same Medicare primary specialty in Marshall, TX — not a recommendation.
Clinician information
| Credential | MD |
|---|---|
| Medical school | University Of Texas Medical School At San Antonio |
| Graduation year | 1988 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| NPI (National Provider Identifier) | 1861489049 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians