Serous cyst adenoma is a cystic ovarian tumor containing a serous fluid and a solid-tissue component. This tumor is a benign form, presenting as a cystic unilocular or a multilocular ovarian mass with a thin wall and minimal papillary projections. Giant ovarian tumors have become rare because of the early detection of adnexal pathology with the advent of routine imaging modalities in the recent era of medical practice. In previous studies, large or giant ovarian cysts were described as cysts measuring more than 10 cm in diameter in a radiological scan or those cysts reaching above the umbilicus. In this study, we report a case of 58-year-old woman who was diagnosed with a right ovarian benign serous cystadenoma measuring 30 × 26 × 24 cm in size with a weight of 5.5 kg.