The acronym CIS may refer to:
- Center for for Comparative and International Studies (Switzerland)
- Center for Internet and Society (Stanford Law School)
- Center for Internet Security
- Central Index System
- Centre for Internet Safety
- Clinical information system
- Commonwealth of Independent States
- Communication and Information Systems
- Communications and information system
- Community Information System
- Copyright Imaging System
- Cryptographic Interoperability Strategy
- Customer information service
- Customer information system