Nearly 80% of patients with Crohn's disease (CD) require surgical treatment for complications or failure of medical management. We managed a 31-year-old man with CD who presented with a post-operative fistula. The patient had undergone surgery due to multiple strictures and a fistula. However, a new fistula developed that connected to the intraperitoneal abscess. Intravenous antibiotics were started and multiple percutaneous drainage tubes were inserted to treat the abdominal abscess. However, the amount of drainage was consistently high, even one month after the operation. To treat the postoperative fistula, 5 mg/kg of infliximab was started, and the amount of drainage decreased dramatically to less than 10 cc a day. Some studies have reported that infliximab decreases the recurrence of CD after surgery. The effect of infliximab on post-operative fistulas in patients with CD has not been sufficiently studied. Our results indicated that the use of infliximab to treat post-operative fistula should be explored further in future clinical studies.