A 78-year-old overweight woman with diabetes mellitus, bronchial asthma, and Sheehan's syndrome on chronic steroid therapy presented with mild short-lived hematemesis, significant hypotension disproportionate to the degree of bleeding and radiographic evidence of cardiomegaly. Endoscopy showed duodenal ulcer. During evaluation of the unexplained brief hypotension and cardiomegaly, 2D-echocardiogram demonstrated anterior and posterior echo-free spaces consistent with large pericardial effusion (PE). However, subsequent elective surgical pericardiotomy unexpectedly revealed large amounts of pericardial fat. Pericardial fat was also noted on magnetic resonance imaging of the chest. Our case illustrates a potential pitfall of 2D-echocardiography in the diagnosis of PE.