Multiple primary malignant tumors are not rare these days with the development of the diagnostic methods. Many studies indicate that the prognosis of synchronous primary tumors is poorer than that of single tumor. The incidence of renal cancer with other primary tumor is rare and also affect the prognosis of the other. Fortunately our transitional cell carcinoma is completely treated with curative resection and does not affect the prognosis itself. We have to try to find out the synchronous cancers and treat them early to lessen the synergistic effect of the multiple cancers. We experienced one case of synchronous gastric and renal cancer. This report summarized our experience and review of literature.