Since (a) obsessive-compulsive disorder (OCD) may involve serotonergic neural transmission abnormalities also though to be related to regulation of suicide and aggression, (b) comorbidity between OCD and depression is substantial, and (c) depression is a major risk factor for suicide, a comprehensive analysis of clinical trial data was undertaken to assess the potential association of fluoxetine, a serotonin uptake inhibitor, and suicidality (suicidal acts and ideation). Pooled data from clinical trials comparing fluoxetine (n = 266) and placebo (n = 89) in patients with DSM-IIIR OCD were analyzed retrospectively. No suicidal acts occurred during placebo lead-in or double-blind therapy. Mean Hamilton Depression Scale item 3 (suicide item) scores improved statistically significantly with fluoxetine compared with placebo. Worsening in suicidal ideation was statistically significantly more frequent with placebo than with fluoxetine. Emergence of substantial suicidal ideation (change in baseline item 3 score of 0 or 1 to 3 or 4) was numerically greater with placebo than with fluoxetine (3.6% vs. 1.7%; not statistically significant). The incidence of suicidality in fluoxetine-treated patients with OCD was low, compared favorably with rates in corresponding placebo-treated patients, and was well within the range of estimates in previous studies of patients with OCD. These controlled clinical trial results suggest no undue risk of suicidality in patients with OCD treated with fluoxetine.