The toxic effect of galactose ethanol feeding to rats was studied by comparing weight changes during isocaloric administration of liquid diets containing 60% of the energy as glucose (diet A), 30% as glucose and 30% as galactose (diet B), 30% as glucose and 30% as ethanol (diet C), and 30% as galactose and 30% as ethanol (diet D). No differences in weight change were found among groups receiving diets A, B, and C, whereas the group fed diet D lost significantly more weight than groups A, B, and C. When the experiment was performed in animals without access to minerals, the death rate of group D was increased. Galactose ethanol feeding increased the hepatic concentrations of galactose 1 phosphate and UDP galactose and decreased the concentration ratios of ATP to ADP and UDP glucose to UDP galactose. It is concluded that feeding galactose and ethanol together depresses growth. It is suggested that the mechanism for this effect is an impairment of the utilization of galactose calories due to ethanol. The possible role of galactose ethanol feeding as an experimental model of galactosemia in humans is discussed.