Thirty-one children, 19 boys and 12 girls, aged 3.4--10.8 years, with severe perennial bronchial asthma were treated with beclomethasone dipropionate aerosol (BDA) for 16-40 months. The dose was initially 400 micrograms a day and was gradually reduced to the lowest level giving control of symptoms. Earlier steroid or ACTH-treatment in six children was stopped during the BDA-treatment. At the start of the treatment the mean deviation of height compared with normal values for Swedish children was -0.10 s.d. for the boys and -0.51 s.d. for the girls. At the end of the observation period the deviation was -0.22 s.d. and -0.58 s.d., respectively. The increase in deviation was not significant. Bone age was also slightly retarded before beclomethasone treatment but this deviation was not accentuated during the observation period. It is concluded that treatment with BDA does not retard growth or skeletal maturation in children. The number of acute admissions to hospital was reduced by more than 50% during the first year of treatment.