Castleman's is an uncommon lymphoproliferative disorder secondary to lymphoid follicle hyperplasia and marked capillary proliferation with endothelial hyperplasia. This illness can be associated with glomerulonephritis (GN). Here, we report a case with steroid-dependent nephrotic syndrome secondary to proliferative mesangial glomerulonephritis in a patient with Castleman's disease, that was diagnosed several years before. Considering the involvement of IL-6 in Castleman's disease we treated the patient with thalidomide obtaining the remission of the nephrotic syndrome. Our experience suggests a possible role of thalidomide in the treatment of glomerular pathology when a role of IL-6 is hypothesized.