Female rats were pair-fed control or ethanol liquid diets on a chronic basis prior to parturition. Six brain regions (hypothalamus, cerebellum, brain stem, cortex, corpus striatum, and hippocampus) were dissected from 19- and 35-day-old rat offspring for the determination of dopamine (DA), sertonin (5-HT), 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindole-acetic acid (5-HIAA), and homovanillic acid (HVA). DA, 5-HT, and the acid metabolites were separated simultaneously by reverse-phase HPLC and were quantitated using electrochemical detection. Between 19 and 35 days of age in control rats we observed an increase in the concentration of 5-HT and 5-HIAA in the corpus striatum and hippocampus and a decrease in these compounds in the cerebellum. In addition, there was a development-related decrease of 5-HIAA in the hypothalamus and an increase in the brain stem. During the same age period the concentration of dopamine increased in the hypothalamus and corpus striatum. There was also a development-related decrease in the concentration of DOPAC in the corpus striatum and an increase in the cortex as well as a decrease in HVA in the cerebellum and cortex. In comparison to age-matched control animals the 19- and 35-day-old offspring of ethanol-treated rats had a lower concentration of 5-HT and/or 5-HIAA in the cortex, cerebellum, and brainstem. In addition the 35-day-old offspring of ethanol-treated rats exhibited a decrease in DA and HVA in the cortex. The results of the present study suggest that in utero ethanol exposure affects both the serotonergic and dopaminergic systems in brain.