COI
COI, CoI or Coi may refer to:
Organizations
- Center on Organizational Innovation, a research center at Columbia University
 - Central Office of Information, a former UK Government department
 - Church of Ireland, an autonomous province of the Anglican Communion
 - College of Idaho, a university
 - Commission de l'Océan Indien, or Indian Ocean Commission
 
Science and technology
- California Oregon Intertie or Path 66, an electrical power transmission system
 - Centre of inertia
 - Coefficient of Inbreeding, the probability that two alleles at a given locus are identical by descent
 - Community of inquiry, a concept describing the social quality of scientific inquiry
 - Community of interest (computer security), a computer networking technique of segregation of resources
 - Confirmed opt-in, a policy for obtaining mailing list recipients
 - Contingency Orbit Insertion, an abort mode of the Apollo spacecraft
 - Cost of illness, see Disease burden
 - Cytochrome Oxidase Subunit 1, a gene
 - Coprocessor Offload Infrastructure, a high-level software library for code and data offloading to a Xeon Phi Coprocessor
 
Other uses
- Comoros, UNDP country code
 - Commission of inquiry (disambiguation)
 - Constitution of India
 - Conflict of interest
 - Certificate of insurance
 - Certificate of incorporation
 - Coi (restaurant), restaurant in San Francisco, California
 - Dennis Coi (died 1987), Canadian figure skater
 - Trịnh Cối (died 1584), Vietnamese de facto ruler of Southern dynasty
 - Coi (album), a 2023 album by Coi Leray