Background: Patients with light chain-predominant multiple myeloma have been shown to exhibit shorter survival. Retrospective comparison of clinical and laboratory data was undertaken to ascertain the likely cause(s) of this observation. Methods: Records of multiple myeloma patients seen at one institution revealed 316 cases of conventional and 71 cases of light chain-predominant multiple myelomas with secretion of intact immunoglobulins. Laboratory and clinical findings in the two groups were compared. Findings: Patients with light chain-predominant multiple myeloma had a significantly higher death rate, higher rate of chronic dialysis, and a lower eGFR and serum albumin, a significantly higher urine protein concentration, and a significantly higher prevalence of hypertension and blood transfusion requirements. Other clinical and laboratory parameters surveyed were not significantly different between the two groups. Interpretation: The shorter survival of patients with light chain-predominant multiple myeloma is likely to be due to renal damage caused by the excess free immunoglobulin light chains. Renal damage might be ameliorated by early aggressive treatment with chemotherapy, plasmapheresis and dialysis; a multi-institutional prospective controlled trial would be needed to test this hypothesis. Funding Statement: None to declare. Declaration of Interests: Dr. Singh serves as a consultant to Diazyme Inc. and HealthTap. All other authors have nothing to declare. Ethics Approval Statement: The study protocol was reviewed and approved by the institutional review board.