Prenatal administration of high doses of tricyclic antidepressants have been reported to produce teratogenic and behavioral effects in rat offspring. In the present work, behavioral abnormalities are described in offspring of rats treated with therapeutic doses of chlorimipramine (CIM) during pregnancy (CIM-P), lactation (CIM-L) and during the whole pregnancy-lactation period (CIM-PL). CIM-P treatment did not produce teratogenic effects, did not affect number or body weight of pups at birth and did not induce neonatal mortality. At 2 months of age, the CIM-P males showed a significant increase in digging and grooming (familiar environment test), a decrease in "exploration" (novel environment test) and a decrease in active social interactions (social behavior test). Females were more resistant than males to the prenatal CIM treatment. The results suggest increased emotionality in CIM-P pups. Some behavioral abnormalities were also observed in the tests performed at 4 months of age. CIM-L treatment had minor effects on litter behavior. CIM-PL treatment potentiated the effects of the CIM-P treatment. In the CIM-PL males, impairment of exploration of a novel environment still remained in the tests performed at 4 months of age. It is speculated that when prenatal brain development is altered by CIM, further postnatal treatment may impair compensatory processes occurring in early postnatal life.