LSI may refer to:
In organizations:
LSI Corporation, a technology company founded in 1981
Lynch Syndrome International, non-profit organisation supporting those affected by Lynch Syndrome
Labour and Socialist International, a multinational federation of left wing political parties and trade unions active between 1923 and 1940
Socialist Movement for Integration (Lëvizja Socialiste për Integrim), a political party in Albania
Lear Siegler Incorporated, a technology company active from 1961-2002
Lingkaran Survei Indonesia, a survey company in Indonesia