IMO or Imo may refer to:

Biology and medicine

* Irish Medical Organisation, the main organization for doctors in the Republic of Ireland * Intelligent Medical Objects, a privately held company specializing in medical vocabularies * Isomaltooligosaccharide, a mixture of short-chain carbohydrates which has a digestion-resistant property * Idiopathic Massive Osteolysis, a name for Gorham's disease

Maritime

* International Maritime Organization ** IMO number, a unique identity number issued to seacraft (pattern "1234567") * SS Imo, SS ''Imo'', a 1889 ship involved in the Halifax Explosion

Meteorology

* International Meteorological Organization * Icelandic Meteorological Office

Other

* International Mathematical Olympiad * International Meteor Organization * Imo State, Nigeria * imo.im, a video calling and instant messaging app * IMO (in my opinion), an Internet slang expression * Integration Management Office see Post-merger integration {{disambiguation