The association of malignant pheochromocytoma and poorly differentiated lymphocytic lymphoma has not previously been reported. A case is presented of a 58-year old man with a 20-year history of malignant pheochromocytoma well controlled on Dibenzyline who was found to have poorly differentiated lymphocytic lymphoma. During lymphoma chemotherapy with cyclophosphamide, vincristine and prednisone (VCP) he developed tachycardia and syncope accompanied by severe hypertension. During the next course of chemotherapy one month later, 24-hour urinary VMA, metanephrine and catecholamine values were determined before, during and after the chemotherapy and were found to have increased two- to ten-fold. This suggests that VCP caused tumor lysis with release of catecholamines into the circulation.