We report results of monitoring treatment in 41 patients with congenital adrenal hyperplasia controlled over 0.3-13.1 years using standard auxological techniques alone. Doses of glucocorticoid (15-25 mg/m2/day) and mineralocorticoid (0.15 mg/m2/day) replacement were determined initially using biochemical indices and thereafter adjusted according to surface area. Monitoring was solely directed at maintaining a 50th centile height velocity for chronological age. Of 41 patients, 32 were referred after the newborn period. Nearly half of these patients were either overtreated or undertreated before their referral. Of the nine treated from birth, all but one were in good control and only two have had a second hospital admission. Present height standard deviation scores (SDS) for chronological age range from -1.60 to -0.26. Height SDS for bone age were compared with midparental heights in 33 patients: 15 treated with early emphasis on growth had a height prognosis exceeding midparental values; patients who had experienced appreciable prior overtreatment or undertreatment fared less well. In the long term management of congenital adrenal hyperplasia correction of salt loss is of primary importance. Doses of glucocorticoid required in addition to mineralcorticoid replacement should be continuously assessed and adjusted to maintain a normal growth velocity. This is most conveniently achieved by standardising replacement doses on surface area.