The frequency of light chain deposition nephropathy relative to renal amyloidosis and Bence Jones cast nephropathy was determined in a necropsy study of 57 patients with myeloma. The diagnosis of light chain deposition nephropathy was established by immunofluorescence microscopic examination of kidney tissue demonstrating linear deposits of a single light chain isotype along tubular and other renal basement membranes, and by electron microscopy, which showed the characteristic granular nature of the deposits. In this study, 3 patients (5%) had kappa light chain deposition nephropathy, 6 (11%) had renal amyloidosis, and 18 (32%) had Bence Jones cast nephropathy. The data indicate that light chain deposition nephropathy is a rare complication of multiple myeloma.