A 58-year-old woman was hospitalized with acute renal failure and unilateral pulmonary consolitation. Ten days later she developed massive pulmonary haemorrhage with diffuse pulmonary consolidation. Renal biopsy revealed 100% crescentic nephritis without immunofluorescence (IF) or electron microscopic evidence of immune-reactant deposition. Circulating anti-glomerular basement membrane (antiGBM) antibody was not detectable by radioimmunoassay. Despite aggressive therapy pulmonary haemorrhage eventually proved fatal. IF of lung tissue revealed no immune-reactant deposition. This report represents a case of idiopathic Goodpasture’s syndrome, both from an aetiological and an immunopathological viewpoint. It emphasizes that Goodpasture’s syndrome (i.e. pulmonary haemorrhage and glomerulonephritis) occurs in a variety of situations which are not mediated by antiGBM antibody deposition and that alveolar haemorrhage should be considered in the differential diagnosis of all radiological pulmonary infiltrates, including unilateral opacities, when abnormalities of renal function coexist.