Paraneoplastic syndrome is defined as tumor-associated symptoms and signs not related to the physical effects of primary or metastatic tumors. The mechanisms of this syndrome include the production of bioactive soluble factors by tumor cells and autoimmune diseases elicited by the immune responses against tumors. Production of bioactive soluble factors causes endocrinologic symptoms. The paraneoplastic autoimmune process may affect the nervous system, cutaneous tissue, musculoskeletal system, hematopoietic cells or kidneys. Paraneoplastic rheumatic diseases show symptoms similar to inflammatory myopathy, polyarthritis, vasculitis, cryoglobulinemia and polymyalgia rheumatica. Rapid onset, unusual age, asymmetrical involvement of joints or refractoriness to standard immunosuppressive therapy suggests the presence of paraneoplastic autoimmune diseases. Autoimmune hematopoietic disorders include pure red cell aplasia, autoimmune hemolytic anemia and thrombocytopenia. Unexplained anemia or thrombocytopenia may indicate the presence of lymphoid neoplasms. Membranous nephropathy is a well-known glomerular disease associated with malignancy, and membranoproliferative glomerulonephritis, minimal change nephrotic syndrome, and antineutrophil cytoplasmic antibody(ANCA)-associated crescentic glomerulonephritis may be seen in cancer patients. Age and sex-appropriate cancer screening should be performed in patients with nephrotic syndrome due to membranous nephropathy.