We describe the case of a 54-year-old man who first presented with a clinical syndrome manifested by recurrent pulmonary hemorrhage, hematuria, and mild renal insufficiency. Direct immunofluorescence of renal biopsy sections showed linear deposition of IgA-kappa in the glomerular (GBM) and tubular basement membranes. Serum protein immunoelectrophoresis was positive for a monoclonal immunoglobulin A (IgA)-kappa protein. Serum analysis showed circulating IgA anti-GBM antibodies. Treatment with high-dose steroids, cyclophosphamide, and plasma exchange resulted in resolution of the clinical picture. To the best of our knowledge, this is the first report of Goodpasture's disease associated with the presence of a circulating monoclonal IgA-kappa antibody.