Zinc is an essential trace element which affects growth by promoting DNA and RNA synthesis and cell division. Zinc deficiency causes growth retardation and its frequency is high in developing countries. It could contribute to the effect of growth hormone (GH) treatment in GH deficient children. In this study, we investigated zinc deficiency in GH children. Twenty-four GH deficient children (treated with GH for 2.2 +/- 1.6 years) were recruited for the study. Intracellular erythrocyte zinc levels were measured. Eleven (45.9 per cent) were found to be zinc deficient (Group 1), while 13 patients (54.1 per cent) had normal zinc levels (Group 2). The mean growth velocity was 5.98 +/- 0.8 cm/year in Group 1 and 6.9 +/- 1.4 cm/year in Group 2. Group 2 was given oral zinc supplementation with a resultant growth velocity of 7.51 +/- 0.5 cm/year. During GH treatment in GH deficient children, zinc status should be evaluated as severe zinc deficiency could affect the response to GH treatment.