A total synthesis of the novel neurotrophic agent (+)-lactacystin (1) has been achieved in 11 steps and 14% overall yield from (2R,3S)-3-hydroxyleucine [(+)-16]. The construction and bioassay of several active analogs are also described. A new asymmetric approach furnished the four stereoisomers of 3-hydroxyleucine, as required starting materials in high overall yield and enantiomeric purity.