Olfactory sensitivity to two odorants, isoamyl acetate and androsterone, was assessed in 14 obsessive compulsive disorder (OCD) patients, nine major depressive disorder (MDD) patients, and 16 sex- and age-matched healthy controls. Tests were performed during a drug-free period, and 3 and 6 weeks after initiation of antidepressant drug therapy. No difference in olfactory sensitivity, to either odorant, was found between OCD patients and controls at any time. In MDD patients, a significant increase in the sensitivity to isoamyl acetate was observed 6 weeks after initiation of treatment, compared to controls.