Thirty-three obese children (5 - 15 years of age) and 15 lean controls (5 - 8 years of age) were included in the study. Zinc content in cell subsets of lymphomonocytes (LMs) and polymorphonuclear cells (PMNc), in plasma and erythrocytes was evaluated. Cell populations were separated by density gradient technique. In obese children the mean level of LMs zinc content was significantly lower than in controls (1.59±0.53 vs 2.18±0.61 nmol/mg of proteins respectively). No significant difference in the zinc content of PMNc, plasma and erythrocytes was found between groups. A significant inverse correlation between LMs zinc content and degree of obesity (percent of overweight and arm-fat area) was observed. The low zinc content in lymphomonocytes may be of relevance as an index of zinc deficiency in obese children. However, the relationship between the zinc content in lymphomonocytes and the immune response still requires further investigation.