Six homologous derivatives (N-butyl 3a, hexyl 3b, octyl 3e, decyl 3d, tetradecyl 3e and stearyl 3t) of [5-valienamine were synthesized. All have been shown to be potent and specific inhibitors of I~-glucocerebrosidase, and to have no potency against glucosylceramide synthase (mouse liver microsomes). Among them, the N-octyl derivative possesses the strongest activity (IC50 3 x 10 .8 M), being almost 10-fold more potent compared to the unsaturated 5a-carba-glucosylceramide 1. Compounds 3b and 3e are also moderate inhibitors of ot-glucosidase (Bakers yeast).