A 41-year-old man presented with physical signs of leg oedema and a laboratory value of decreased serum albumin of 2.4 g.dl-1. Loss of protein via the gastrointestinal tract was demonstrated by an increased faecal excretion of 51-chromium-labelled-albumin and by elevated stool clearance of alpha 1-antitrypsin. No anatomical lesions or intestinal disease were found to explain this protein loss. Constrictive pericarditis was suspected as the cause of protein-losing enteropathy but could not be confirmed by right heart catheterization, in which normal filling pressures and no sign of 'dip and plateau' pressure pattern were found. However, magnetic resonance imaging clearly demonstrated a thickening of the pericardium over the right heart and a tubular-shaped right ventricle as signs of constrictive pericarditis. Peripheral oedema disappeared and serum protein concentration returned to normal after pericardectomy. This demonstrates that moderate pericardial constriction not resulting in discernible pressure abnormalities in the right heart can be associated with protein-losing enteropathy and thus result in hypoproteinaemic peripheral oedema. In this condition a morphological investigation by magnetic resonance imaging is of importance in order not to miss the diagnosis of a potentially treatable disease.