The authors studied the effects of 6 months of zinc therapy on cell-mediated immunity in regular dialysis therapy patients. Serum zinc was significantly enhanced (p less than 0.01) at 2 months. While cells, OKT3, and OKT4 did not show significant variation, but after 6 months of therapy a significant (p less than 0.02) decrease of OKT8 cells, with enhancement of the OKT4/OKT8 ratio, and a significant (p less than 0.01) increase in the Multitest Composite score were found. At the same time, a significant elevation (p less than 0.001) of adenosine triphosphate (ATP), and a reduction (p less than 0.01) of lymphocyte adenosine monophosphate was seen; consequently, energy charge levels increased. Zinc-induced improvement of uremic lymphocyte function is likely mediated by an increase in intracellular ATP.