BACKGROUND Peutz-Jeghers syndrome (PJS) and mesenteric fibromatosis (MF) are rare diseases, and PJS accompanying MF has not been previously reported. Here, we report a case of a 36-year-old man with both PJS and MF, who underwent total colectomy and MF surgical excision without regular follow-up. Two years later, he sought treatment for recurrent acute abdominal pain. Emergency computed tomography showed multiple soft tissue masses in the abdominal and pelvic cavity, and adhesions in the small bowel and peritoneum. Partial intestinal resection and excision of the recurrent MF were performed to relieve the symptoms. METHODS A 36-year-old male patient underwent total colectomy for PJS with MF. No regular reexamination was performed after the operation. Two years later, due to intestinal obstruction caused by MF enveloping part of the small intestine and peritoneum, the patient came to our hospital for treatment. Extensive recurrence was observed in the abdomen and pelvic cavity. The MF had invaded the small intestine and could not be relieved intraoperatively. Finally, partial bowel resection, proximal stoma, and intravenous nutrition were performed to maintain life. CONCLUSIONS Regular detection is the primary way to prevent deterioration from PJS. Although MF is a benign tumor, it has characteristics of invasive growth and ready recurrence. Therefore, close follow-up of both the history of MF and gastrointestinal surgery are advisable. Early detection and early treatment are the main means of improving patient prognosis.