A 42-year-old patient with acute left-ventricular failure is described in whom pheochromocytoma was diagnosed only after prolonged and fruitless efforts. Pheochromocytoma may present without the typical features of paroxysmal or sustained hypertension, headache, increased sweating, and palpitations. Therefore, in cases of acute left-sided cardiac failure of primarily undetermined origin, pheochromocytoma should be considered in differential diagnosis.