It is just in recent years that mitochondrial DNA (mtDNA) mutations have been found in solid tumors. Although a direct link between the presence of mtDNA mutations and the development of tumors has not been made, mtDNA mutations might prove significant in the detection of tumor recurrence and possibly in the detection of genotoxic damage. To investigate the relationship between mtDNA variation and endometrial cancer, we collected blood samples from subjects with Han native background in Yunnan province in China, 49 of them with pathologically conformed endometrial cancer and 31 as controls with no cancer disease and sequenced two hypervariable segments of control region, part of 16sRNA gene, tRNA(leu) (tRNA is transfer RNA) gene and ND1 gene of mtDNA and identified some diagnostic polymorphisms by restriction fragment length polymorphism of coding region of mtDNA. We could not identify the suspected mutations that are related to diabetes and obesity from our endometrial cancer patients. However, our data showed that patients with endometrial cancers clustered in haplogroup D in a significantly higher frequency when compared with controls, implicating a possible association of haplogroup D to endometrial cancer. We concluded that mitochondrial polymorphisms in haplogroup D might play a genetic role in predisposing to endometrial cancer.