We herein report the case of a 53-year-old white acromegalic patient with an abdominal mass due to massive cardiomegaly. The patient suffered from long lasting acromegaly refractary to bromocriptine, transsphenoidal surgery and radiotherapy. He had been previously diagnosed as having systemic hypertension, ischemic chest pain and congestive heart failure with marked cardiomegaly. The present admission was due to asthenia, anorexia and weight loss that were finally attributed to adrenal insufficiency secondary to radiotherapy. Plain abdomen X-ray suggested the presence of supramesocolic mass. A large cold area in the left hepatic lobe was detected on the radionuclide liver scan. Radionuclide angiography surprisingly identified the cold area as a vascular structure corresponding to the heart. A body CT scan revealed the heart was expanding between stomach and liver. Two-dimensional echocardiography showed marked enlargement of left ventricle. Cardiomegaly was probably multifactorial (chronic hypertension, ischemic heart disease and acromegaly). To our knowledge, this is the first reported case of massive cardiomegaly behaving as an intraabdominal mass. This possibility must be considered when invasive intraabdominal diagnostic procedures are to be done, particularly in an acromegalic patient. © 1987 Martinus Nijhoff Publishers.