Colouterine fistula, secondary to diverticulitis, is an extremely rare complication, and only few cases have been reported in the literature. We report the case of 76-year-old woman, who presented with vaginal discharge over a three-month period. Pelvic examination and laboratory investigations suggested a colouterine fistula, that was confirmed by non-invasive imaging. Surgical treatment was a one-stage, en bloc resection of the uterus and sigmoid colon. In the presence of severe inflammatory reaction or paracolic abscess, a two-stage procedure should be safer. Otherwise, a one-stage procedure, en bloc resection of the uterus and sigmoid colon is preferred, as we cannot rule out a malignancy prior to surgery.