Among 3492 patients with ovarian tumors subjected to operation between 1/1957 and 3/1994 at the Department of Obstetrics and Gynaecology at the University of Rostock 620 (17.8%) cases of teratomas were found. Histology findings, age, tumor size, bilaterality and malignity of these 620 cases were analyzed. The histologic differentiation yielded 604 (17.3%) mature teratomas (dermoid cysts), 15 monodermale and 1 immature teratoma. Division of total period in the time before and after 1990-since then we have got the possibility of laparoscopic operation-reveals that presumably by increasing use of ultrasound a decrease in mean age at time of diagnosis from 40.2 +/- 20 to 30.7 +/- 12 as well as in tumor size (9 +/- 4 resp. 4 +/- 2 cm) has been achieved. A secondary malignant transformation of epithelial component has been found in 0.5% (3/604) and bilaterality in 11% of the cases. With regard to general rules of laparoscopic operations the intact dermoid cyst enucleation is recommended in premenopausal and extirpation in postmenopausal women. For opening, reduction of volume, and removal of the dermoid cyst from the abdominal cavity, an endo-bag or endo-catch respectively should be used.