The galactose elimination capacity was calculated from both arterial and capillary or peripheral venous curves in twenty patients. The capillary curves on the average were delayed 1.4 min in relation to the arterial curves. No significant difference was found between the calculated galactose elimination capacity from either curve. On the average the slope of the venous curves was smaller than that of the arterial curve, and their time delay was very variable (from 1.55 to 5.27 min). Galactose elimination capacity calculated from venous curves was smaller than those calculated from arterial curves, especially in patients with a high galactose elimination capacity. Capillary blood sampling may replace arterial puncture for routine use, whereas venous blood sampling introduces a significant bias.