The placental transport of alcohol and its effect on maternal and fetal acid-base balance studied in 10 sheep experiments by the maternal infusion of a 9.75 per cent solution of alcohol-dextrose at a rate of 15 c.c. per kilogram for 1 or 2 hours. Serial maternal and fetal blood sampling during and following the alcohol infusion revealed rapid placental diffusion of alcohol, a highly significant correlation between maternal and fetal blood alcohol concentrations, and a similar peak concentration of approximately 0.230 Gm. per 100 ml. in maternal and fetal blood that differed only in time of onset during the 1 and 2 hour infusion periods. Blood alcohol concentrations remained high for several hours during the postinfusion period. A significant maternal hyperlactacidemia and hyperglycemia were noted but did not result in significant alterations in maternal acid-base balance. An initial fetal metabolic acidosis and later mixed acidosis were observed during the alcohol infusion and worsened during the postinfusion period.