IMS
- IBM Information Management System
- IMS Associates, Inc.
- IMS Bildbyrå
- IMS Health
- IMS International Medical Services
- IMS Unison University
- IP Multimedia Subsystem
- Imaduddin School
- Immunomagnetic separation
- Ims
- Indian Mathematical Society
- Indian Medical Service
- Indian Mini Satellite bus
- Indian Missionary Society
- Indianapolis Motor Speedway
- Industrial methylated spirit
- Insight Meditation Society
- Institute of Management Studies, Devi Ahilya University
- Institute of Mathematical Statistics
- Institute of Medical Sciences, Banaras Hindu University
- Insulated metal substrate
- Integrated Medical Systems International
- Integrated Micro Solutions
- Integrated master schedule
- Intelligent Micro Software
- Intelligent Munitions System
- Intelligent maintenance system
- International Magicians Society
- International Measurement System
- International Micropatrological Society
- International Military Staff
- International Monitoring System
- International Mountain Society
- International Music Summit
- International Musicological Society
- Internet Map Server
- Internet Medieval Sourcebook
- Intramuscular stimulation
- Ion mobility spectrometry
- Iowa Mennonite School
- Iranian Mathematical Society
- Irish Marching Society
- Irish Mathematical Society
- Irritable male syndrome
- Ministry of Defence (United Kingdom)
- Porsche Intermediate Shaft Bearing issue