Isolated unilateral ovarian tumour without obvious concomitant tubal pathology is unlikely to cause intrabdominal abscess or septicaemia. Benign serous cystadenoma is a fairly common ovarian tumour but rarely causes fatality. We present a patient in mid-30s with massive ovarian serous cystadenoma presenting with abscess and septicaemia, leading to mortality. To our knowledge, no previous serous cystadenoma causing abscess formation has been reported before.