The operative treatment of chronic contained rupture of a saccular abdominal aortic aneurysm (AAA) with retroperitoneal haematoma is reported. A 62-year-old man presented with a painless abdominal mass and intermittent claudication. He had an episode of severe abdominal pain about 2 years before admission. A giant retroperitoneal neoplasm was initially suspected, based on computed tomography. However, magnetic resonance imaging, angiography and colour Doppler sonography demonstrated chronic contained rupture of an AAA. A punched-out oval defect (width 3.5 cm length 4.5 cm) that was thought to connect the thrombosed aneurysm to an organized retroperitoneal haematoma was discovered in the posterior wall of the bifurcation of the aorta at laparotomy. An infrarenal aortobiexternal iliac Y-graft with bypass to the left femoral artery was placed without removing the aneurysm or haematoma. Recovery was uneventful. The retroperitoneal haematoma appeared smaller on computed tomography about 1 year after operation. This case fulfulled the criteria for chronic contained rupture of an AAA proposed by Jones and associates.