The ingestion by normal adults of a standard oral glucose load (75 g) resulted in a significant decrease of the fasting rate of urinary excretion of the trace metal chromium. This effect was not accompanied by any significant parallel change in GFR. Copper excretion rate was not significantly changed by the glucose load. In contrast with the effect of a glucose load, diuresis, induced by a water load, increased the excretion rate of both chromium and copper by more than 100%. The increases in metal excretion with diuresis were not attributable to increased GFR.