OBJECTIVE It has been proposed by some investigators that trichotillomania, a disorder of chronic hair pulling, is a variant of obsessive-compulsive disorder, and some studies have suggested that the antiobessional agents clomipramine and fluoxetine are useful in treating this disorder. The authors investigated the efficacy of fluoxetine in the treatment of trichotillomania. METHODS Twenty-one adult chronic hair pullers were recruited into an 18-week placebo-controlled, double-blind crossover study of fluoxetine, in doses up to 80 mg/day. The fluoxetine and placebo treatment phases consisted of 6-week trials of each agent separated by a 5-week washout period. Fifteen subjects (14 female and one male) completed the study; an additional female subject dropped out at 16 weeks after developing a drug reaction. RESULTS No significant Drug by Period interactions were found in weekly subject ratings of hair pulling, weekly subject ratings of the urge to pull hair, weekly assessments of the number of hair-pulling episodes, or the estimated amount of hair pulled per week. CONCLUSIONS The short-term efficacy of fluoxetine in the treatment of trichotillomania was not demonstrated in this study.