Five days after a blunt trauma with intrarenal rupture of a renal cyst, whereby temporarily a calyceal communication had formed, there was a spontaneous second rupture of the cyst with excessive retroperitoneal haemorrhage. Surgical treatment was necessary and could be accomplished without nephrectomy. Both an arterial bleeding at the bottom of the cyst and a several days' old renal infarction at the edge of the cyst seemed to be relevant for the two-stage rupture. The sonographic, urographic and surgical findings are reported.