Highly active antiretroviral therapy (HAART) has significantly improved the prognosis of HIV(+) in children. Human immunodeficiency-associated lipodystrophy syndrome (HALS) is a side effect of HAART seen predominantly in adults and less often in children. Leptin is a protein thought to play an important role in body composition and has been shown to have immunomodulatory effects. We retrospectively studied serum levels of leptin in a cohort of eight HIV-infected children followed prospectively before and during HAART and investigated whether there is a correlation of these levels with the clinical, immunological, viral or nutritional changes observed during treatment in these children. None of our children developed HALS. In this small cohort of children, we found that serum leptin levels were appropriate to the nutritional status of the patient and that leptin/BMI increased in patients who responded to HAART. In conclusion, in HIV(+) children during HAART, leptin levels are related to the nutritional status of the child.