Pregnant Wistar rats were maintained on a diet of food pellets and a 10% (v/v) solution of ethanol in water during pregnancy and up to 21 days postpartum. Control groups were given food pellets and water ad libitum. The consumption of food and liquid was monitored throughout this period, so that daily food- and ethanol-derived caloric intake, daily liquid intake, and dose of alcohol ingested could be determined. The body weights and whole brain weights of ethanol-exposed offspring did not differ significantly from controls at any time from birth up to 21 days postpartum. However, cerebellar weights were significantly reduced in 21-day-old ethanol-exposed offspring. Areal analysis of the cerebellar vermis showed a 9% reduction in 21-day-old ethanol-exposed offspring compared with controls. Although there were no differences in total vermal area between control and treated rats at 12 days, ethanol-exposed offspring had a significantly more extensive external granular layer. In midgestation, pregnant females registered peak alcohol levels of 118 mg/100 ml blood 1 hr prior to the end of the dark cycle, while during lactation peak levels of 135 mg/100 ml blood were obtained. Neonate alcohol levels peaked slightly later and reached much lower values (44 mg/100 ml blood) during the lactation period. Ingested alcohol intake and blood alcohol levels fall within the range associated in man with the fetal alcohol syndrome, and it is suggested that the experimental regime described is a useful method for invest gating the effects of alcohol on the developing nervous system.