The identification of biotransformation products of the new choleretic drug epomediol in rat has been performed by means of mass spectral, proton magnetic resonance and infrared techniques. The drug was administered perorally or intravenously; urine, bile and faeces were collected and the metabolites isolated. In urine, three metabolites were found in addition to the unchanged drug, namely; 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-hydroxy-7-one, 1,3-dimethyl-2-oxabicyclo[2.2.2]octan-6,7-hydroxy-10-methanol and 1,3,3-trimethyl-2-oxabicyclo[2.2.2.]octan-6-beta-glucuronide-7-ol. In bile only the glucuronide and the unchanged drug were found. Analogously, in faeces the glucuronide and the drug were also identified, but only in trace amounts. This fact may suggest the presence of an enterohepatic circulation of the drug.