The abdominal cavity cysts most frequently observed in female babies are lateral ovarian cysts. These cysts may be detected as early as during the prenatal ultrasound examination, most often at the third trimester of pregnancy. Both the cysts diagnosed prenatally and postnatally are mostly asymptomatic, and in the majority of cases spontaneously regress; therefore, they require only observation during the subsequent ultrasound examinations. However, if the changes are of a diameter greater than 4-5 cm, show rapid growth with acute abdominal symptoms, or cause diagnostic difficulties, the decision concerning surgical treatment must be made. Selection of the method of treatment still remains a subject for discussion, and the development of surgical techniques provides increasingly greater possibilities. Nevertheless, irrespective of the selected method, it is most important that the surgical treatment is of the character maximally sparing the normal structure of the ovary.