1. Benzhexol and three of its metabolites excreted in urine in man have been investigated by g.l.c.-mass spectrometry. 2. Three isomeric hydroxylated metabolites were identified as the 1-(hydroxycyclohexyl)-1-phenyl-3-piperidinopropan-1-ols. 3. The amounts of benzhexol and its identified metabolites have been semiquantitatively determined after a single oral dose in two healthy adults. Approx. 56% of the dose was excreted as the hydroxylated metabolites. The levels of benzhexol excreted were too low to be measured by the techniques used.