Background: Urachal carcinoma is a rare non-urothelial malignancy involving the midline or dome of the bladder due to direct extension from the urachal ligament. There is currently no standard chemoterapy for urachal cancer of stage IV, unavailable to operate. We report a rare case of metastatic urachal cancer treated by FOLFOX (5-FU,leukovorine,oxaliplatin), considering its pathological resemblance to colon cancer. Case report:?A 39-year-old man came to our institution for abdominal extension for weeks. An abdominal CT was performed in March 2016, which showed an irregular low density mass about 5×7cm in size at lower abdomen, between UB dome and umbilicus, extending to extraperitoneal space and large amount of ascites with infiltrations at omentum (A). The patient had some elevated serum tumor markers,including a CEA of 22.84 and CA 19-9 of 424.93. Tumor biopsies demonstrated mucinous adenocarcinoma of urachal mass and metastasis to omentum (C,D). Considering Stage IV state according to MD Anderson criteria, a systemical chemotherapy of gemcitabine and cisplatin was started in April. However, due to disease progression, which showed elevated tumor markers as a CEA of 29.42 and CA 19-9 of 1131.24. we changed regimen to FOLFOX in June. After two series of FOLFOX treatment, a CT in july showed no increase of mass size and a marked decrease of ascites (B). Moreover, turmor markers had been decreased as a CEA of 27.40 and CA 19-9 of 880.16. Conclusions:?A good treatment response to urachal cancer has been made by using FOLFOX regimen.