Pyometra, an accumulation of pus within the uterine cavity, is a rare gynecologic disease with an incidence of 0.01-0.5% among all gynecologic patients and 13.6% among elderly gynecologic patients. Pyometra in itself is rare, much so is uterine rupture occurring secondary to it. No local data reporting incidence of ruptured pyometra in the Philippines has been published. This is a case of a 63-year-old Gravida 5 Para 5 (5-0-0-4), with Cervical Endometrioid Adenocarcinoma Stage IIIB, presented with abdominal pain. Whole abdominal Computed Tomography scan revealed pneumoperitoneum. Initial assessment was pneumoperitoneum probably secondary to ruptured viscus. The patient underwent exploratory laparotomy which revealed ruptured pyometra. Subsequent management included drainage, culture guided antibiotics, radiotherapy and brachytherapy. Spontaneous rupture of pyometra is a serious medical condition which requires an accurate diagnosis in order to arrive in appropriate surgical and medical management. However, pre-operative diagnosis is difficult despite the presence of advanced imaging techniques, hence high level of suspicion is warranted in identifying this condition.