Tsoi or TSOI may refer to:
- Geto Heaven Remix T.S.O.I. (The Sound of Illadelph), an album by American hip-hop artist Common
- Tsoi, Lavongai Rural LLG, Papua New Guinea
- Viktor Tsoi, Russian singer
- Anita Tsoy, Russian singer-songwriter
It may also be an alternative spelling of two different surnames:
- Cai (surname), a Chinese surname, in Cantonese pronunciation
- Choi (Korean name), especially as a transcription of the Cyrillic 'Цой'