Objective: To assess whether in prepubertal children insulin secretion is pulsatile as in adults and to study the influence of body weight on the pattern of insulin secretion. Design and Patients: Insulin profiles were obtained by 4-min sampling for 2 h, starting at 08.00 a.m. after an overnight fast in 10 prepubertal obese children (BMI-SDS 4.9 ± 1.6) and in 6 healthy age-matched controls. Five of the obese children were also studied after weight reduction (Δ BMI-SDS 1.6 ± 0.4). The data have been analyzed by the Pulsar program. Results: Obese children had higher mean insulin levels, insulin secretory areas under the curve above 0 (AUC₀), and AUC above baseline (AUCb), with more frequent peaks of larger amplitude and duration compared to controls. Following weight reduction there was a normalization of AUC₀ and mean insulin levels while AUCb, peak frequency, amplitude and duration did not change significantly. Correlation analysis revealed that BMI-SDS was strictly related to the parameters of pulsatile insulin secretion such as AUC₀, AUCb, mean insulin level, peak amplitude and peak frequency. Conclusions: Insulin secretion in children is pulsatile and its secretory pattern is influenced by body weight.