51 surgically treated cases with hormone-producing tumours of the adrenal cortex are evaluated for the reliability of preoperative localisation of diagnostic measures and postoperative results. 6 patients were children. The group contains 14 cases of Conn's syndrome, 32 cases of hypercortisolism, including 3 children, and 5 cases of AGS, 3 of which were children. The recommended work-up procedure is initiated by ultrasonography and followed by CT, possibly in combination with adrenal scintigraphy. This combination of a morphological and functional investigation established the correct diagnosis in all 51 cases. Laboratory values returned to normal levels in all cases, phenotypical aspects normalised in most cases. Deaths and complications occurred only in hypercortisolism and AGS.