Giant ovarian adenomas are rarely observed today because of early diagnosis and treatment. Mucinous cystadenomas is a kind of tumor that mostly causes the ovary to enlarge. Theu can present with various and non-specific clinical manifestations such as deep vein thrombosis. The primary symptoms of giant ovarian tumors are abdominal enlargement and distension. Therefore, making the correct preoperative diagnosis is sometimes difficult. The appropriate treatment must include oncologic procedures and a multidisciplinary approach to minimalize complications and save the patient's life. Herein, we report a woman aged 53 years with a 27-kg ovarian mucinous cystadenoma that presented as a left popliteal vein thrombosis.