Ovarian Sertoli-Leydig cell tumors (SLCT) are rare sex cord stromal neoplasms. To date there have been approximately 25 case reports of ovarian SLCT expressing alpha-fetoprotein (AFP). In such cases, AFP was immunohistochemically detected in the Sertoli cells, Leydig cells, or hepatocytes. This case report confirms heterologous gastrointestinal epithelium expression of AFP. A 20-year-old woman presented with complaints of abdominal enlargement and irregular menstrual cycles over one year. A right ovarian tumor was detected and the patient's serum AFP was elevated. A right salpingo-oophorectomy was performed. On microscopic examination, the tumor was composed of a fibrosarcoma-like area and a poorly differentiated SLCT area with heterologous gastrointestinal epithelium. Immunohistochemical analysis detected AFP in the gastrointestinal epithelium only. Postoperatively, serum AFP levels fell to normal. A recurrent tumor was discovered in the omentum after adjuvant chemotherapy, but serum AFP remained normal. A second laparotomy was performed and the recurrent tumor showed only fibrosarcoma-like features. The patient received second line chemotherapy and is currently in remission. This is the first case of AFP production by heterologous gastrointestinal epithelium in SLCT.