Subnormal plasma zinc levels and decreased zinc concentration in hair and leucocytes as well as increased plasma ammonia and ribonuclease activity in dialyzed and nondialyzed uremic patients indicate that zinc metabolism is abnormal in uremia and is not corrected by dialysis. The effect of oral supplementation with zinc acetate (12 patients) or placebo (12 patients) on the above biochemical parameters in hemodialysis patients was determined as a part of a double-blind study. The zinc-supplemented, but not the placebo, group demonstrated significant increases in mean (+/- SD), plasma zinc (80 +/- 9 to 110 +/- 14, micrograms/dl), leucocyte zinc (56 +/- 13 to 1098 +/- 18, micrograms/10(10) cells), hair zinc (140 +/- 12 to 190 +/- 16 micrograms/g), and decreases in plasma ammonia (76 +/- 10 to 40 +/- 6 micrograms/dl) and plasma ribonuclease activity (1.49 +/- 0.08 to 0.78 +/- 0.10, OD/min/ml). Abnormalities of taste and sexual function improved significantly in patients receiving zinc but not in those on placebo therapy. These improvements in biochemical as well as clinical parameters confirm and extend our earlier observations of improvement in taste and sexual function after zinc supplementation. Together, they suggest that zinc deficiency is a complicating feature of uremia and can be corrected by oral zinc supplementation.