Objective: The aim of this study was to follow auxological parameters and their relationship to serum growth hormone-binding protein (GHBP) and leptin levels in children with acute lymphoblastic leukemia (ALL). Design and methods: In total, 26 prepubertal children with ALL were studied. We report these data at the time of the clinical diagnosis (n 26) and at 6 (n 21), 12 (n 21), 18 (n 21), 24 (n 20), 30 (n 16) and 36 months (n 16) after beginning treatment. Results: Serum GHBP levels decreased during the ®rst 18 months and returned to normal when therapy was withdrawn. Height SDS increased at 24 months after diagnosis. Weight and the upper arm circumference had increased 6 months after chemotherapy withdrawal, whereas tricipital and subscapular skinfolds had increased both at 6 months after diagnosis and 6 months after therapy had stopped. Therefore, the tendency to become overweight is both an early and a late side-effect of anti-leukemia therapy. A signi®cant positive correlation was found between serum leptin levels and every nutritional anthropometric parameter, with body mass index having the best relationship. However, serum GHBP levels were only correlated with BMI at the end of the study. No correlation was found between leptin and GHBP. Conclusions: In children with ALL, linear growth is compromised during the acute phase of their illness and therapy; this is probably secondary to a state of partial and transient GH insensitivity. These patients tend to become obese after therapy withdrawal, with leptin being an excellent nutritional marker.