Effects of long-term ethanol consumption by pregnant rats have been investigated on the protein synthesis by fetal and neonatal brain ribosomes. Chronic ethanol-feeding to pregnant rats resulted in about 30% decrease in the rate of 14C-leucine incorporation by the fetal cerebral ribosomes. The rate of 14C-leucine incorporation by the cerebral ribosomes from neonatal rats suckling on ethanol-fed mothers showed about 60% decrease as compared to the corresponding control group. The brains from both fetuses and neonates of the ethanol-fed group showed a decrease in the amount of t-RNA formed compared to the corresponding controls. The highest rates of 14C-leucine incorporation into ribosomal protein were observed by ribosomes from neonate brains. The ribosomes from fetal brains showed the highest sensitivity to the in vitro addition of ethanol. Pretreatment with cycloheximide significantly inhibited the rate of 14C-leucine incorporation into the ribosomal protein. The cerebral content of both total RNA and DNA was significantly lower in the brains of developing neonates suckling on ethanol-fed mothers compared to the corresponding controls.