The tricyclic anti-depressant clomipramine (7.5 or 15 mg/kg/day) was administered to pregnant rats between days 8 and 21 of gestation. Between postnatal days 31 and 47, both male and female offspring received three behavioural test. Prenatal clomipramine (15 mg/kg/day) increased baseline acoustic startle in females, but not in males; both sexes showed greater between-day response decrements if they had received clomipramine. In the social interaction test of anxiety, males prenatally exposed to clomipramine (both dosages), and females prenatally exposed to 7.5 mg/kg/day, revealed a similar profile to that seen after chronic administration of benzodiazepines in the adult. The likelihood that differences in within-session habituation could underlie the changes in social interaction that have been found in this and other studies is assessed.