About 20% of children with nephroblastoma at onset present with macroscopic haematuria, which is usually asymptomatic and of little clinical relevance. The Authors describe an unusual case of nephroblastoma presenting with massive haematuria causing extensive blood clothing along the urinary tract and bladder. The phenomenon was of such entity to determine urinary retention and induce performing emergency nephrectomy. Tumour resection was radical and postoperative course uneventful. Eighteen months after surgery patient is in excellent status and full remission.