ABSTRACT Background: Spontaneous rupture of gangrenous uterus with generalized peritonitis in postmenopausal women is a very rare entity usually caused by pyometra and is associated with high morbidity and mortality. The clinical findings of perforated pyometra are similar to perforation of the gastrointestinal tract which makes preoperative diagnosis difficult. A correct and definite diagnosis can be made with laparotomy or laparoscopy. We report a case of a 55-year-old lady who presented with generalized peritonitis with pneumoperitoneum. This report aims to alert surgeons to the possibility that perforation of uterus due to gangrene with anaerobic infection also shows air under diaphragm apart from hollow viscus perforation.