We report a rare case of primary aldosteronism with severe hypokalemic myopathy in a 59-year-old female who had suffered from hypertension since 1979. Because of severe muscle weakness, especially of extremities, she became unable to rise from her bed and was admitted to the Kitagawa hospital on July 10, 1989. Symptoms such as tetany, polyuria, and diarrhea were not observed. Her consciousness was clear. The blood pressure was in the range of 152 mmHg systolic and 104 mmHg diastolic. Systolic heart murmur (Levine II), cardiac arrythmia, and slight edema on the legs were noticed. She did not have any sign of muscular atrophy. Serum aldosteron level was 220 pg/ml, and plasma renin concentration was less than 0.5 ng/ml/h. The serum level of potassium was 1.7 mEq/l, sodium 150 mEq/l, GOT 47 IU/l, LDH 507 IU/l, CPK 850 IU/l (MM type 99%), and aldolase 9.2 mIU/ml. Computed tomography (CT) after intravenous contrast injection revealed a round low density mass (1.6 cm in diameter) in her left adrenal gland. CT also revealed the gallbladder adenomyomatosis. Her left adrenal gland and gallbladder were surgically removed on July 26, 1989. After the operation, the blood pressure and laboratory data including serum potassium returned to normal, and she became able to pursue her ordinary life. Endoscopy revealed a gastric polyp which was hyperplastic. Histopathologically the removed adrenal gland showed an adrenocortical adenoma consisted of clear cells and nodular hyperplasia of the glomerular zone.