Cast Nephropathy/Light chain tubulopathy is usually present in patients with multiple myeloma and is very rare in patients with Waldenstrom Macroglobulinemia. There are very few case reports mentioned in the literature. We present an interesting case of Cast Nephropathy and light chain tubulopathy in an 81-year-old female patient with Waldenstrom Macroglobulinemia who required medical attention for worsening renal failure. Serum protein electrophoresis/Immunofixation showed IgM Kappa monoclonal gammopathy. Renal biopsy was remarkable for cast nephropathy and light chain tubulopathy. Furthermore on bone marrow biopsy a low grade B cell lymphoproliferative disorder with plasmacytic differentiation was present. This was most consistent with lymphoplasmacytic lymphoma, accounting for 50-60 percent of total bone marrow cellularity, in a hypercellular (60-80 percent) bone marrow.