Endometrial cancer of young (less then 40 years old) patients comprises 4-5% of all endometrial cancers in Hungary. The majority of patients did not give birth yet, so fertility sparing is very important. Fertility sparing treatment is possible if the tumor's histology is endometrial type and Grade 1 (well differentiated). The tumor localizes only to the endometrium and there is no myometrium infiltration. The authors present 17 cases of patients treated at the Department of Gynecology of National Institute of Oncology (Budapest, Hungary). In 3 cases conservative therapy (progesterone treatment) was possible, and 14 patients had to undergo surgery, because conservative treatment did fail. Of 17 patients 14 were never pregnant. The average patient's age was 32.35 ± 4.27 years. The mean body weight was 93.13 ± 30.79 kg (from 58 kg up to 147 kg); in 7 cases BMI (body mass index) was more than 30. After surgery histological examination had revealed 2 cases with normal ovaries, 1 case of simple cyst and 1 case of malignant ovarian tumor (serous adenocarcinoma, Grade 2), and 10 cases of polycystic ovaries associated with endometrial cancer. Of 3 cases that had only curettage, the endometrial cancer was Grade 1, and in 1 case radiological imaging showed simplex ovarian cyst. The authors' findings concerning young endometrial cancer patients confirm the results published in the literature. In cases suitable for fertility sparing treatment it is not sufficient to concentrate only on endometrial findings, but is very important to focus on the therapy of cystic ovaries (80% of which is PCO), obesity and diabetes mellitus as well.