This study focuses on the diagnostic and therapeutic challenge posed by spontaneous perirenal haematomas (SPHs). The medical records of 18 patients with SPHs seen in the past 8 years were reviewed with respect to aetiology, diagnosis and therapeutic management. SPH was secondary to angiomyolipoma (n = 4), polycystic kidneys (n =4), panarteritis nodosa (n = 3), renal cell carcinomas (RCCs, n = 2), glomerulonephritis, pyelonephritis, Morbus Wegener and cortical adenoma (one each). One case remained unclear. With appropriate imaging techniques (computed tomography and angiography) the underlying disorder was detected in 72%; in 4 cases the diagnosis was revealed by exploration and biopsy. Surgery was necessary in 16 patients. The cause of bleeding can be revealed by appropriate imaging in most cases. When imaging procedures fail to reveal the cause of SPH, exploration and biopsy are mandatory to exclude RCC. If the cause of SPH remains unclear even after exploration, patient monitoring by CT is justified.