OBJECTIVE As overweight is a major concern in many children with Turner syndrome, we studied the effect of growth-promoting treatment with human growth hormone (hGH) on body weight indices. METHODS Longitudinal study of the effect of hGH on weight indices over time in a cohort of Turner girls of different ages. METHODS An index group of 199 hGH treated girls and a reference group of 569 untreated girls. METHODS Turner-specific weight-for-age, weight-for-height and body mass index-for-age (BMI) values were computed. In order to take account of regression to the mean, we studied spontaneous changes of these variables in the reference group. References for spontaneous changes over 3, 6, 12 or 24 months were constructed. Observed changes in the index group were corrected by subtracting the expected spontaneous change. Corrected changes were compared between overweight, normal and underweight children. RESULTS Treatment with hGH leads to a temporary decrease of weight indices during the first six months. This decreasing effect was not seen in overweight children. Treatment increases BMI in overweight children over 24 months, but not in normal or underweight children. BMI at start of hGH treatment did not modify long-term growth response. CONCLUSIONS hGH treatment does not help to improve BMI in Turner syndrome children with a tendency to overweight.