Adrenal tumors may be divided into three groups, stromal, medullary and cortical. All adrenal tumors should be removed as soon as they are discovered because of the danger of malignancy. The non-hormonal tumors produce no signs or symptoms until a palpable mass is found. In the malignant group, metastasis may be discovered before the primary tumor is palpable. The hormone-producing tumors are from the medullary portion of the adrenal or from the cortical. The only medullary hormone producing tumor is the pheochromocytoma which causes an increase in the pressor amines. Clinically, this is evidenced by hypertension, either sustained or paroxysmal. The diagnosis is incontrovertible when the pressor amines are found in excess but the tests are difficult. Screening tests are helpful but not infallible. The best of these tests are the histamine provocative test in the normotensive patient, and the regitine adrenergic blocking test in the hypertensive patient. Presacral oxygen insufflation and intravenous pyelograms may localize the tumor. Aortography should not be performed. If localization is not possible, the patient should be explored transabdominally and in addition to exploring the suprarenal areas, paragangliomas should be looked for along the sympathetic ganglia. Since hypertension, due to this tumor, is almost always cured by the removal of the tumor, physicians should be alert to detect this growth. Cortical hormonal tumors may produce either of three clinical pictures: (1) Primary aldosteronism is characterized by periodic severe muscular weakness, intermittent tetany and paresthesia, polyuria, polydipsia and hypertension. Elevated urinary aldosterone establishes the diagnosis although other findings are characteristic, such as low serum calcium with elevated potassium, pH and carbon dioxide combining power. (2) Androgenic cortical cell tumors cause virilism. Fortunately, since the diagnosis is more easily made in the female, the tumor occurs four times as often in the female as in the male. (3) Adrenocorticoid tumors produce Cushing's syndrome. The surgical removal of cortical tumors produces cures in the non-malignant cases and in the malignant cases when cortical tumors can be totally removed before metastasis has taken place. A series of twenty-nine tumors of the adrenals, discovered in a period of six years, is reported. Reports are given of five cases in which surgery was performed.