Sis
- American University
- Australian Secret Intelligence Service
- Canadian Security Intelligence Service
- Cis (disambiguation)
- Ciss (disambiguation)
- Finnish Security Intelligence Service
- GSI Helmholtz Centre for Heavy Ion Research
- Information and Security Service of the Republic of Moldova
- John Herzfeld
- Kozan, Adana
- LAPD Special Investigation Section
- Los Angeles Police Department
- Magic (cryptography)
- McGill University School of Information Studies
- Michael Sis
- Mountains of Sis
- New Zealand Security Intelligence Service
- Police tactical unit
- SIS (Soft Is Strong)
- SIS (file format)
- SIS (group)
- SIS (motorbikes)
- SIS Swiss International School
- Safety instrumented system
- Saline infusion sonography
- Schengen Information System
- School of International Service
- School of International Studies of the Dresden University of Technology
- Second-impact syndrome
- Secret Intelligence Service
- Security Information Service
- Selective inverted sink
- Seoul International School
- Sequential Importance Sampling
- Sequential infiltration synthesis
- Serviço de Informações de Segurança
- Sex in space
- Sharjah Indian School
- Shekou International School
- Shimano Index Shifting
- Short integer solution problem
- Shoulder impingement syndrome
- SiS (talk show)
- Siemens IT Solutions and Services
- Signals Intelligence Service
- Silicon Integrated Systems
- Silicon monosulfide
- Singapore International School
- Singapore International School Mumbai
- Single-image stereogram
- Single-instance storage
- Singular isothermal sphere profile
- Sis (ancient city)
- Sis Rural District (Dehgolan County)
- Sis Rural District (Shabestar County)
- Sis, Armenia
- Sis, Azerbaijan
- Sis, Iran
- Sis, Kurdistan
- Sissy
- Sister
- Sisters in Islam
- Slovenská informačná služba
- Small intestinal submucosa
- South Island School
- Space Infrastructure Servicing
- Special Intelligence Service
- Special Investigations Section (disambiguation)
- Sports Information Services
- State Information Service
- Stockholm International School
- Strategic information system
- Student information system
- Superconductor-insulator-superconductor tunnel junction
- Supervised injection site
- Surabaya International School
- Survey of India Service
- Swedish Institute for Standards
- Swedish National Board of Institutional Care
- Syracuse University School of Information Studies
- United States National Library of Medicine
- University of Pittsburgh School of Information Sciences
- Washington, D.C.