Aldosterone is a major regulator of the body potassium stores through its role in potassium excretion by the kidney. However, it is unclear whether aldosterone affects transcellular distribution of potassium in atrial myocytes, and whether hypokalemia associated with primary hyperaldosteronism increases susceptibility to atrial fibrillation (AF). We report a case of a 58-year-old male with Conn's syndrome in whom symptomatic AF was related to hypokalemia.