Previous studies of Golgi-impregnated material demonstrated the vulnerability of the dendritic arbors of the CA1 pyramidal cells of the hippocampus and the Purkinje and granule cells of the cerebellum to perinatal exposure to ethanol. The purpose of this investigation was to determine whether the alterations seen in the Golgi material could be corroborated at the ultrastructural level, and to qualitatively survey the neuropil surrounding the affected neurons. Pregnant mice were maintained on either a chocolate-flavoured liquid diet containing 25% of its caloric value as ethanol (5.4% v/v) or a chow and water diet. The treatment period began on gestational day 12 and continued until postnatal day 7, at which time the ethanol-exposed animals were returned to a chow and water diet. Pups were killed on postnatal day 14, and the tissue was processed for ultrastructural and Golgi analysis. The results confirm our Golgi findings that ethanol severely compromises the dendritic arbor, and also indicate that ethanol exposure produces changes in the organization of the neurophil, as well as alterations in the organization of the perikaryal organelles, and glial swelling.