The authors discuss the radiological signs in 18 patients with an adrenal tumour. 7 of them had a Cushing's syndrome, 10 others a phaechromocytoma and the last had primary hyperaldosteronism. The diagnosis was made from the history, the clinical picture, hormone estimations and pharmacodynamic tests, whilts in the majority of cases the tumour was localised by radiodiagnosis. In all cases, there was hypertension, permanent in tumours of the adrenal cortex, paroxysmal or permanent in the cases of pheochromocytomas. We emphasise the importance of retro-pneumoperitoneum, as the radiological investigation of choice, in the localisation of adrenal tumours, especially pheochromocytomas, and in Cushing's syndrome. In cases of pheochromocytoma, one should follow carefully the blood pressure, during special radiological investigations, in view of the danger of a sudden rise or fall in blood pressure, the first is treated with phentolamine, the second with noradrenaline solution. Finally, a scan using I 131 19-iodocholesterol may be valuable in diagnosis and localisation of adrenal tumours; it has in particular given very encouraging results in the differential diagnosis of adrenal tumours with the clinical presentation of Cushing's disease.