We present the case of a 48-year-old patient with a recurrent rectovaginal fistula, who we treated surgically by transposing the gracilis muscle. The patient with a history of ulcerative colitis underwent colorectal resection with mechanical anastomosis and diverting ileostomy for rectal cancer. She was subsequently treated by radiation and chemotherapy. Six weeks later, the ileostomy was removed, but afterwards the patient developed a recto-vaginal fistula. A new diverting ileostomy was performed. After eight months, a transvaginal surgical procedure was performed, and the diverting ileostomy was closed after four months. Two years after the last surgery, the patient performed an MRI scan, which revealed the relapse of the rectovaginal fistula. This time the patient was reoperated using a flap of the gracilis muscle interposed between the rectum and the vagina, but the patient refused any diverting stoma. The rectovaginal fistula relapsed again after thirteen days. Fortunately, after six months of intensive systemic and local treatment with aminosalicilic-5-acid, the fistula closed by itself. Our conclusion is that with a well-managed medical treatment, the gracilis flap, because of its good vascular supply, could be successfully used to treat rectovaginal fistulas even in patients with ulcerative colitis who underwent rectal surgery and radiation therapy for cancer.