To investigate renal function in a group of patients with a history of haemophilia and haematuria. We reviewed 32 medical records of the patients with haemophilia and gross haematuria identified through a computerized haemophilia registry, from January 1993 to December 2004. In all patients but three (two refused to participate and one died) clinical and laboratory tests were performed by the nephrologist. One patient had chronic renal failure because of diabetic nephropathy. In two patients reduced renal function was detected by creatinine clearance measurements, and one of them had Duchenne muscular dystrophy. In four patients minimal proteinuria was diagnosed by the biuret method. Mild reduction in renal function of unknown cause was found in only one of the 29 patients tested.