Acetylleucine (N-acetyl-leucine) is a modified leucine amino acid.
Two forms are commercialized: N-acetyl-<small>DL</small>-leucine (sold under the brand Tanganil, among others, and used in the treatment of vertigo) and N-acetyl-<small>L</small>-leucine (levacetylleucine, sold under the brand name Aqneursa, and used for the treatment of neurological manifestations of Niemann-Pick disease type C).