// Officer Designator · O-1 to O-10 · NATO OF-1 to OF-9

MEDICAL SERVICE CORPS OFFICER (2300)

The Staff Corps community of Navy healthcare specialists, scientists, and administrators.

Insignia

Designator

2300

Abbreviation

MSC

Community

Staff Corps

Paygrade Range

O-1 to O-10

NATO Range

OF-1 to OF-9

OVERVIEW

The 2300 Medical Service Corps (MSC) designator identifies Staff Corps officers in the U.S. Navy who serve as healthcare specialists across 31+ distinct subspecialties — including pharmacy, physical therapy, occupational therapy, clinical psychology, social work, optometry, podiatry, audiology, dietetics, healthcare administration, biomedical engineering, microbiology, environmental health, industrial hygiene, and more. MSC officers are the science, allied-health, and administrative backbone of Navy Medicine.

Each subspecialty has its own commissioning prerequisites — typically a master's or doctoral degree in the relevant field, plus state licensure or board certification where applicable. MSC officers serve at Navy hospitals and clinics, biomedical research commands, operational units afloat and ashore, and Marine Corps commands as embedded specialty providers and healthcare administrators.

The MSC is unusually broad: a clinical psychologist supporting a Marine Expeditionary Unit, a research microbiologist at the Naval Medical Research Command, a hospital comptroller at Naval Medical Center Portsmouth, and an industrial hygienist surveying a shipyard all wear the same MSC oak-leaf-and-acorn device. This breadth gives commanders a single Staff Corps to call on for almost any non-physician, non-dentist, non-nurse healthcare expertise the Navy needs.

RESPONSIBILITIES

Provide allied-health, behavioral-health, or science specialty support to Navy Medicine
Lead healthcare administration at a Navy hospital, clinic, or operational unit
Conduct biomedical research at the Naval Health Research Center or Naval Medical Research Command
Serve as operational specialty officer with Fleet Marine Force or expeditionary units

HISTORY

The Medical Service Corps was established by Congress on August 4, 1947, consolidating the previously-separate Hospital Corps Officer, Pharmacist, Optometrist, and Sanitary Engineer Corps officer programs into a single staff corps. The new corps was modeled on the Army Medical Service Corps, established the same year, and gave Navy Medicine a unified pipeline for the rapidly expanding allied-health and biomedical-science professions emerging out of the Second World War.

The MSC has expanded steadily over the decades to incorporate new healthcare specialties as they have emerged — adding clinical psychology, social work, healthcare administration, biomedical engineering, environmental health, and more — and today fields more than 2,500 active-duty officers across more than 31 distinct subspecialties, making it one of the most diverse Staff Corps in the Navy and a critical contributor to operational medicine, research, and Navy Medicine enterprise leadership.

COMMISSIONING SOURCES

Direct Accession (most subspecialties)
Health Services Collegiate Program (HSCP)
Lateral Transfer

TRAINING PIPELINE

1. Officer Development School (ODS)~5 weeks
Naval Station Newport, RI
Direct-commission officer indoctrination required for all Staff Corps accessions.
2. Subspecialty Internship / Residency12–36 months (varies)
Navy or joint teaching hospital
Subspecialty-specific clinical or administrative residency training.
3. Operational Medicine Course~2 weeks
Camp Pendleton, CA / Camp Lejeune, NC
Operational medicine indoctrination prior to Fleet Marine Force tour.

TYPICAL CAREER PATH

O-1/O-2
ODS + first MSC tour
Officer Development School followed by first specialty practice or administrative tour.
O-3
Specialty Practice or Internship
Subspecialty-specific clinical practice or administrative residency.
O-4
Department Head
Department head at a Navy hospital or operational specialty leadership tour.
O-5
Senior MSC Leader
Senior subspecialty leadership or major-staff billet at Navy Medicine HQ.
O-6
Major Command
Command of a Navy clinic, research command, or healthcare-administration command.

RELATED DESIGNATORS

RELATED BASES

How to address

Verbally by rank — e.g., "Lieutenant Commander Smith." Doctorate-holders may be addressed as "Doctor Smith" in clinical settings.

Prerequisites

Master's or doctoral degree in a designated MSC subspecialty (pharmacy, PT, psychology, optometry, healthcare administration, etc.)
Subspecialty-specific licensure or certification where applicable
Successful completion of Officer Development School (ODS)
Maintain Secret clearance and operational medical fitness

Common assignments

Pharmacist, physical therapist, optometrist, or psychologist at a Navy hospital
Healthcare administrator at a Navy military treatment facility
Operational specialty officer with a Marine Expeditionary Force unit
Research scientist at a Navy biomedical research command

FREQUENTLY ASKED QUESTIONS

The 2300 designator identifies a Staff Corps officer in the Navy Medical Service Corps — a healthcare specialist in one of 31+ subspecialties supporting Navy Medicine.

The MSC includes pharmacy, physical therapy, occupational therapy, clinical psychology, social work, optometry, podiatry, audiology, dietetics, healthcare administration, biomedical engineering, microbiology, environmental health, industrial hygiene, and more — over 31 distinct subspecialties.

Some do. Operational subspecialties — psychology, physical therapy, environmental health — often serve with Fleet Marine Force units or aboard hospital ships USNS Mercy and USNS Comfort.

SOURCES

Last updated 2026-05-02

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