The metabolism and elimination of 3H-butorphanol (levo-3, 14-dihydroxy-N-(cyclobutylmethyl)[15-3H]morhinan) tartrate were determined in man after therapeutic im (2 mg) and iv (1 mg) doses. As judged from urinary excretion of radioactivity, the im dose was completely absorbed. Butorphanol was rapidly distributed to tissues, had a plasma half-life of about 3 hr, and was extensively metabolized prior to elimination. The major route of elimination was renal, with fecal excretion being a minor route. Hydroxybutorphanol [3, 14-dihydroxy-N-(trans-3'-hydroxycyclobutylmethyl)morphinan] was isolated and identified as a major urinary metabolite and was also present in the plasma. The disposition of butorphanol is compared and contrasted to the disposition of morphine and pentazocine.