Abstract: Objective：To study clinical characteristics of patients with endometrial carcinoma under 40 years old. Methods：To study endometrial carcinoma cases who were treated from December 2004 to December 2012 retrospectively. Those patients were divided into two groups，which were 20 cases（4%，20/498） at age of less than 40 years in early onset group and 478 cases with more than 40 years age in general group. Clinical characteristics，risk factors，treatment，pathological type，histological grading，myometrial invasion，lymph node metastasis and adnexal metastasis between two groups were reviewed and compared. Results：The percentage of primary infertility patient in early onset group was 30.0%（6/20），The percentage of normal group was 4.2%（20/478）. The difference was statistically significant（χ2=25.855，P=0.000）. The incidence of hypertension in early onset group is lower than the normal group（χ2=7.954，P=0.003）. All early onset group patients were endometrioid adenocarcinoma. The percentage of endometrioid adenocarcinoma in normal group was 78.5%（375/478），the difference was statistically significant between two groups（χ2=5.433，P=0.020），90% early onset group patients were histological grade G1，49.8% normal group patients were histological grade G1，the percentage of stage Ⅰ in early onset group was 80%，the percentage of stage I in normal group was 74.1%，the difference between histological grade （Z=-8.259，P=0.000） and clinical stage （Z=-9.488，P=0.000） was statistically significant. There were no statistical significance between two groups in deep myometrial invasion, cervical invasion and lymph node metastasis，adnexal metastasis and positive abdominal dropsy cytology （P＞0.05）. Conclusions：Young women occupy a certain proportion of endometrial cancer，infertility is a high risk factor for endometrial cancer whose age is under 40 years，major pathological type is endometrioid adenocarcinoma，histological grade tend to be G1，young patients tend to be diagnosed at an early stage，deep myometrial invasion，cervical invasion and lymph node metastasis，adnexal metastasis and positive abdominal dropsy cytology are similar to the elderly patients，etc.

Key words: Endometrial neoplasms, Carcinoma, endometrioid, Retrospective studies, Age factors, Early onset