Disorders of taste and smell are underrecognized and often misdiagnosed. Two cases are described in which patients mistakenly thought to suffer from depression actually had unnoticed drug-induced dysosmia and dysgeusia. Also reviewed are psychiatric, neurologic, and medical disorders and drugs that cause abnormalities of taste and smell, and some behavioral aspects of food aversions. Three groups, all of whom may superficially appear depressed, must be distinguished from each other: 1) patients with dysosmia or dysgeusia, 2) patients with primary neuropsychiatric illness with olfactory or gustatory hallucinations, and 3) patients with conditioned taste aversions.