OMS may refer to:
- Office Master System - An Enterprise Resource Planning vendor; Office Master System, Inc.
- Old Millfieldians - alumni of Millfield School; also used as in the OM Society.
- List of Old Marlburians - alumni of Marlborough College
- O'Banion Middle School — Garland, TX
- Odle Middle School — Bellevue, WA
- Orefield Middle School — Orefield, PA
- Otte-Blair Middle School — Blair, NE
- Odorless Mineral Spirits
- Office of Muqtada al-Sadr
- One Mission Society - a Christian missionary society
- Oracle Management Server an executable component of Oracle database servers
- Manuel de Oms y de Santa Pau - apparatchik in the War of Spanish Succession, Viceroy of Peru
- Ontario Motor Speedway
- Open Media Commons
- Open Metering System a standardization effort in the field of smart meter
- Open Music System, once widely-used MIDI interface software
- Opsoclonus myoclonus syndrome
- Optical Multiplex Section, the optical section layer that multiplexes wavelengths within the Optical Transport Network
- Oral and maxillofacial surgery
- Orbital Maneuvering System - rocket engines used on the Space Shuttle orbiters
- Order Management System
- Osteopathic Medical Student, a student Doctor of Osteopathic Medicine. -I, -II, -III -IV indicate the year in school.
- Outage management system
- Organization for the maintenance of supplies
- Omsætningsafgift, a Danish tax.
- One Minute Silence, a metal band
- IATA code for Omsk Tsentralny Airport
- Oms, Pyrénées-Orientales, a commune in southwestern France
- Online Marketing Specialist
- Online Marketing Summit a trade show, conference and workshop for marketing and internet professionals
- Open Mobile System, the system used by OPhone