This development of pathology in conserved ovaries is defined as the residual ovary syndrome (ROS). It consists of pelvic pain, pelvic mass, dyspareunia as a single or a cluster of symptoms. It is estimated that at least 5% of patients will develop ROS and require surgery for it following hysterectomy. We describe a case of ROS in a 41-year-old woman who developed an abdominopelvic mass the size of a pregnancy of 24 weeks' gestation within 11 weeks of hysterectomy and right salpingo-oophorectomy. At laparotomy, the mass was found to be a huge benign ovarian cyst measuring 11.5 x 11.0 x 14.1 cm. Histology showed benign thick-walled follicular cysts. ROS can occur 'acutely', our case having the shortest latent period of onset ever reported.