BACKGROUND Ovarian dermoid cysts are one of the most common benign neoplasms in women. Rarely, serious complications occur that result in life-threatening events such as bowel perforation. This case summarizes one of these complications from clinical presentation to diagnosis and treatment. METHODS A 25-year-old woman with symptoms of small bowel obstruction was found to have a 10-cm dermoid cyst perforating into both her small and large bowel. A primary large bowel repair and small bowel resection with en bloc left salpingo-oophorectomy and small bowel side-to-side reanastomosis was performed. CONCLUSIONS This case illustrates the rare formation of a fistula between a dermoid cyst and the small and large bowel. Awareness of the clinical and radiologic findings in these cases is important to avoid further complications.