Prenatal cocaine exposure can result in neurobehavioral disturbances and structural modifications of the central nervous system. In the present study, cocaine was injected into pregnant rats and the brains of their offspring were examined at the light microscopic level. As adults, cocaine-exposed offspring exhibited subtle, but consistent, hippocampal abnormalities. In particular, the stratum pyramidale (particularly the CA1 region) was interrupted by frequent gaps in lamination, and ectopic pyramidal cells were found in stratum oriens and radiatum.