The time courses of capillary and venous blood concentrations of ethanol after oral administration of 0.30 and 0.34 g/kg doses of ethanol to two normal human subjects indicated that, by interpolation, equal capillary and venous concentrations are reached at only one time, and this time varied with the subject. The capillary/venous blood concentration ratios varied markedly as a function of time in both subjects over the entire observation period of 4 h.