The authors describe a case of 21-year-old man suffering from tuberous sclerosis, more than once operated for subependymal astrocytomas, presenting multiple bilateral renal angiomyolipomas of 1.5 cm as greatest diameter. Last abdominal ultrasonographic exam, done a few years after the former, revealed an angiomyolipoma measuring 10 cm in diameter at the upper pole of the right kidney. This angiomyolipoma projected into a large haematoma of 15 cm in diameter, absolutely asymptomatic. After CT control bone lesions were removed. This case shows the progressive increase in number and size of renal angiomyolipomas, with subsequent haemorrhagic complications, suggesting as opportune periodic ultrasonographic controls.