The title compound, stigmasta-5,22-dien-3beta-ol hemihydrate, C(29)H(48)O x 0.5H(2)O, previously thought to be the monohydrate, has two sterol molecules and one water molecule in the asymmetric unit. In both sterol molecules, the methyl group of the ethyl substituent at the end of the hydrocarbon chain is disordered over two sites. The OH group of molecule A donates a hydrogen bond to a water molecule and accepts a hydrogen bond from the OH group of molecule B. The OH group of molecule B accepts two hydrogen bonds from water molecules.