Background and objective To study the clinicopathoiogical characteristics of Lynch syn＆ome-associated endometrial carcinoma in China.Methods Twenty-seven patients who fulfilled the Amsterdam Criteria Ⅱ were classified as having Lynch syndrome-associated endometrial carcinoma (Group A), and 331 patients without a family history of cancer were classified as having sporadic endometrial carcinoma (Group B).Results There were 81 malignancies in 27 Lynch syndrome-associated endometrial carcinoma families, including colorectal cancer (CRC, 24.7%), endometrial carcinoma (21.0%), liver (12.3%), stomach (9.9%), lung (6.2%), and breast (6.2%) cancers. Mean age at time of diagnosis was 49.7 years in Group A and 56.3 years in Group B (P=0.004). Second primary cancers occurred in 33.3% of patients in Group A and 5.1% in Group B (P<0.0001). "Ihe most common second primary cancers were colorectal cancer (44%) and ovarian cancer (22%). The percentage of obese patients was higher in Group A (P=0.013). There was no difference between the two groups in incidence of diabetes mellitns or hypertension or in histological type and FIGO stage. The 5-year survival rates for Group A and B were 96.2% and 79.6%, respectively. Prognosis for Group A was better than for Group B (P=0.045).Conclusion Some clinicopathologicai features of Lynch syndrome-associated endometrial carcinoma, such as early onset and multiple primary carcinomas, are similar in the Chinese and American/European populations. However, the Chinese population had a unique family cancer distribution that included lung and breast cancers. An increased number of grade 1 endometrioid tumors and a better prognosis imply better biobehavior in Chinese Lynch syndrome-associated endometrial carcinoma. Obesity may be a co-contributing factor for development of Lynch syndrome associated endometrial cancer in China.