Four prepubertal children with chronic growth retardation (growth velocities less than or equal to 4 cm/yr), normal growth hormone (GH) response to provocative stimuli and low basal but increased somatomedin activity values after GH administration, received continuous GH-therapy (4 IU/three times a week) for an 18-24-month period. Growth velocity doubled during the first 12 months of therapy and remained 4-6 cm/yr until the end. Bone age progressed according to chronological age and adult height predictions improved. No thyroid function or carbohydrate and lipid metabolism anomalies were observed. After completion of this GH-therapy period, patients remained off treatment during the following six months. Growth velocities were similar to pre-GH-treatment values in two patients, lower in the third and higher in the fourth, who was by then pubertal. Thus, in these patients, long-term GH-therapy promoted growth and improved adult height prediction.