We report a highly unusual case of monoclonal immunoglobulin deposition disease-associated nephrotic syndrome in which a patient developed both lambda light chain deposition disease and 6 years afterward IgG-heavy chain amyloidosis. The patient initially underwent autologous peripheral blood stem cell transplantation as treatment of the underlying plasma cell dyscrasia causing the light chain deposition disease-related nephrotic syndrome. After 6 years of clinical remission, recurrence of the nephrotic syndrome led to a renal biopsy demonstrating IgG-heavy chain amyloidosis. Interestingly, much of the characteristic nodular glomerular sclerosis seen in light chain deposition disease regressed between the time of the first biopsy and the second. Given the length of time between the development of the two diseases and the apparent success of stem cell transplantation in treating the first, we think that the patient produced two distinctly different abnormal plasma cell clones. To our knowledge, this is the first report of two different monoclonal immunoglobulin deposition diseases occurring in the same patient.