Girls with Turner's syndrome are characterized by growth retardation and defective pubertal development, among other features. In this investigation, 40 girls with Turner's syndrome were treated with growth hormone in doses of 0.1 IU/kg/day (group 1, n = 14), oral oestradiol in doses of 0.01 mg/kg/day (group 2, n = 8) or a combination of these (group 3, n = 18), depending on the bone age. All three forms of treatment increased the height velocity significantly. The combined treatment increased the height velocity more than the growth hormone of oestradiol alone (p less than 0.05). In group 2, a pronounced progression of bone age leading to a decrease in the prognosis of final height was observed. The serum insulin-like growth factor I was unchanged in group 2 while this rose in groups 1 and 3. Pubertal development was, by and large, satisfactory. No serious side effects were observed. Treatment of girls with Turner's syndrome with growth hormone should not be supplemented with oestrogen prior to the bone age of 11 years. The initial dosage of oestradiol should be less than 0.01 mg/kg/day, but the subsequent increase should be adjusted individually.