Four metabolites and unchanged octoclothepin were extracted with dichloroethane from the urine of humans given octoclothepin. These substances were isolated and purified by column and thin-layer chromatography. 2. By chromatographic, spectrophotometric and polarographic analysis, unchanged octoclothepin and three of the metabolites were identified (noroctoclothepin, noroctoclothepin S-oxide and octoclothepin S-oxide). 3. The presence of glucuronides in human urine was proved. 4. The same metabolites and unchanged octoclothepin were also found in rat urine by chromatography.