Previous studies suggest that growth hormone (GH) may increase daily zinc requirements to meet the demand of growing bone and to replace increased urinary losses. We tested the hypothesis that zinc or copper availability might be limiting factors in the response of children receiving GH replacement. Ten patients with GH deficiency were followed for GH-induced changes in urine and serum zinc and copper during acute (0.3 IU/kg/day×5 days) and chronic GH treatment (0.1 IU/kg/tiw). Zinc was measured in hair collected every 3 months. Zinc sulfate (220 mg/day) was given to half the patients during the second year of treatment. There was no evidence of zinc or copper deficiency, and zinc supplements did not venhance growth response to GH during the second year of treatment. We conclude that GH treatment in children does not alter serum or urine zinc or copper or hair zinc, and zinc supplementation does not improve growth in children with GH deficiency.