A patient with Goodpasture's syndrome is described in whom pulmonary manifestations were dramatic, but in whom renal abnormalities were minor and only found on fluorescent and electron microscopy. His urine showed no proteinuria and no increase in cells in quantitative counts, and renal function was normal. It is suggested that there may be an indication for carrying out renal biopsies in patients with idiopathic pulmonary haemosiderosis and that this may lead to an early diagnosis of Goodpasture's syndrome.