SummaryThe growth-inhibiting effect of exogenous corticosteroids has been reported in many papers. Most of them have concerned the clinical problems of asthma and rheumatoid arthritis but it is probable that the underlying disease is relatively unimportant in determining the effect on growth. Steroid therapy on alternate days seems to produce less undesirable effects than steroid treatment every day and corticotrophin may be preferable.Although the mechanisms are uncertain it seems likely that the action is peripheral and certainly exogenous growth hormone does not prevent the steroid effect. A minimal dosage of corticosteroids should always be used in replacement therapy for hypopituitarism.THE harmful effects of glucocorticoids on growth are well known to all clinicians who treat children. In general, this is recognized in the management of bronchial asthma, rheumatoid arthritis and the nephrotic syndrome, as these are the most common childhood disorders that are treated with long-term corticosteroids. This poor growth may also be associated with a degree of maturational delay, which is usually observed as delayed skeletal age. The mechanism of this effect on growth and how to prevent it is not known. Investigation of the various conditions in which it occurs can, however, give us valuable insight into the pathogenesis of the poor growth and perhaps suggest ways of avoiding it.Growth retardation has long been recognized as a feature of childhood Cushing's syndrome where the source of excessive glucocorticoids is endogenous. Prader, Tanner and von Harnack (1963) described a girl who had suffered with Cushing's syndrome from 4 months to 4 years of age, at which time an adrenal adenoma was removed. By the time of the operation she was 5 2 s.d. below the mean of stature for age although her weight was well above the mean. The growth velocity over the 2 years before the operation was 3 -2 cm/year but following the surgery it increased rapidly so that it was 17-8 cm/year during the subsequent year. Growth velocity remained above the Correspondence: M. A. Preece,