IMO may refer to:
- International Mathematical Olympiad
- International Maritime Organization
- IMO ship identification number, unique identity numbers issued to seacraft (pattern "1234567")
- International Meteorological Organization
- Icelandic Meteorological Office
- International Meteor Organization
- Idiopathic Massive Osteolysis, a name for Gorham's disease
- Independent Market Operator of Ontario, Canada—now the Independent Electricity System Operator (IESO)
- Irish Medical Organisation, the main organisation for doctors in the Republic of Ireland
- Intelligent Medical Objects
- IMO (in my opinion), Internet slang expression
- In the matter of
Read more about IMO: Imo