Leptospiral pathogens have a world-wide distribution and cause a spectrum of disease ranging from a mild, influenza-like illness to Weil's disease, which manifests itself in multi-organ failure. Recently, Leptospira-reactive sera from 40 leptospirosis patients were investigated in an ELISA designed to detect antibodies to the human glomerular basement membrane (GBM). The aim was to determine if host-derived leptospiral immunoglobulins cross-react with proteins in the human GBM, so facilitating the development of Goodpasture's syndrome. As all 40 sera were found negative in the anti-GBM ELISA, the hypothesis that, during the immune phase of leptospirosis, patients are at risk of developing Goodpasture's syndrome was not supported. Further work is required to determine if leptospirosis is a risk factor in the development of any other pulmonary-renal syndromes that are associated with auto-immune diseases, such as Wegener's granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome, Behçet's disease, IgA nephropathy and systemic lupus erythematosus.