Recently we have encountered a case of primary aldosteronism due to the left adrenocortical adenoma. Conn in 1954 first described this new syndrome, which is characterized by outstanding features as hypertension, muscle weakness, periodic paralysis, renal and electrolyte abnormalities namely mild proteinuria, severe and persistent hypokalemia. The case reported here, died of uremia-like symptom and a small adrenocortical adenoma was found at autopsy. In the clinical feature, although this case presented no muscle weakness nor periodic paralysis we diagnosed from other clinical findings and the results of examinations as a primary aldosteronism.Case History.