Leptin, a hormone from adipose tissue, regulates feeding behavior, satiation rate, energy expenditure and also plays an important role in maturation and reproduction. Recent studies support the concept that several factors such as a diet may influence on leptin levels. The aim of this study was to investigate serum concentration of leptin and lipids status in prepubertal children aged from 2 to 10 years with two different nutritional habits: vegetarian (n = 24) and omnivorous diet (n = 20). Serum leptin concentration was determined by immunoenzymeassay (ELISA). Serum lipids (cholesterol, HDL- and LDL-cholesterol, triglyceride) were measured by enzymatic and apolipoproteins by immunoturbidimetric methods. We noticed that in vegetarian diet there is a high rate of fiber (nearly twice as high as in omnivorous diet) and polyunsaturated acids (35% as much). In our study vegetarian children had lower total cholesterol and cholesterol in fractions HDL and LDL than meat eaters did. Also the apolipoproteins levels in vegetarian children were significantly below that of nonvegetarians. There is no differences in triglyceride concentration between the two groups of children. The mean serum leptin level in vegetarian children was significantly lower (3.1 +/- 1.2 ng/mL) as compared with the omnivores (5.6 +/- 2.1 ng/mL) (p < 0.0001).