SYNOPSISThe pattern of steroid excretion of a female infant with congenital adrenal hyperplasia was examined on the fifth day of life.The absence of pregnanetriol and the pattern of steroid excretion indicated a 3β‐ol‐de‐hydrogenase deficiency; DHA and other androgens were excreted as sulphate (solvolysable) conjugates. On the other hand, the presence of 11‐oxygenated steroids in the urine did not support this diagnosis. The detection of significant quantities of reducing steroids excreted as sulphate conjugates, suggested that either the corticosterone or cortisol pathway was partially open.An ACTH stimulation test at 3 1/2 months of age while the patient was receiving dexamethasone, revealed significant quantities of pregnanetriol in the urine, and a decrease of those steroids excreted in the neonatal period. It is suggested that the ACTH test is a valuable aid in the post neonatal period in the diagnosis of difficult cases of congenital adrenal hyp