To determine whether both ethanol and fructose increase the plasma concentration of uridine, we administered ethanol (0.6 g/kg) or fructose (1.0 g/kg) to seven normal subjects. Both ethanol and fructose increased the plasma concentration of uridine together with an increase in the plasma concentration of oxypurines, whereas fructose also increased the plasma concentration of uric acid, but ethanol did not. In ethanol ingestion and fructose infusion, an increase in the plasma concentration of purine bases correlated with that of uridine. These results strongly suggest that an increase in the plasma concentration of uridine is ascribable to increased pyrimidine degradation following purine degradation increased by ethanol and fructose.