The role of the insulin-like growth factor I (IGF-I) system and nutritional status was studied in 241 children from a Brazilian area endemic for visceral leishmaniasis (VL). Thirty-nine children had the active form, 20 were oligosymptomatic, 38 were asymptomatic and 144 were not infected. Serum concentrations of growth hormone (GH), total and free IGF-I and IGF binding-protein 3 (IGFBP3) were measured by radioimmunoassay. Nutritional status was evaluated by anthropometric indicators and biochemical measurements. Total and free IGF-I and IGFBP3 were significantly reduced in the active form. Z scores for total and free IGF-I and for IGFBP3 were found to be significantly lower for active VL and oligosymptomatic individuals than for asymptomatic individuals, but never reached values <or=2 SD. Median values of weight-for-age Z and height-for-age Z (HAZ) scores and albumin concentration were significantly different in the active VL group compared with the other groups. Multiple discriminant analysis selected albumin and HAZ score as predictors of active and oligosymptomatic VL. The lack of correlation between auxological data and serum concentrations of the GH/IGF axis components suggested that the primary cause of retarded growth in children with active VL is not dependent on IGF-I or IGFBP3, but rather on VL intrinsic factors that might secondarily involve the GH/IGF axis.