ALT is an abbreviation for alanine transaminase, an enzyme in the liver.

ALT is also the name of a band, the members of which are Andy White (Irish Musician), Tim Finn and Liam O'Maonlai.

ALT is also an abbreviation for Assistant Language Teacher, the job title of people on the JET Programme.

ALT was also an acronym by the NASA for the Approach and Landing Tests of the Space Shuttle in 1976.

ALT can mean alternative lengthening of telomeres, a mechanism (other than telomerase) that cells use to maintain telomere length.