A 50-year-old woman with Beçhet's disease presented with episodic diarrhoea and generalised abdominal pain. She was on regular mycophenolate maintenance therapy, being intolerant of both ciclosporin and azathioprine. Previous rectal biopsy was consistent with colitis, probably associated with Beçhet's disease. During this admission, she began passing faecal matter per vaginam. Digital rectal examination confirmed the presence of a large rectovaginal fistula. She underwent urgent laparotomy for a subtotal colectomy with end ileostomy. Although there were no signs of septicaemia preoperatively, small perforations were identified in the caecum and at the splenic flexure on laparotomy. Histopathology confirmed the presence of multiple shallow ulcers throughout the colon with features suggestive of Beçhet's colitis.