Objective.To identify the A3243G mutation of mitochondrial(mt) DNA in patients with latent autoimmune diabetes mellitus in adults (LADA) of Han nationality in the northeast area of China. Methods.Seventy nine diabetics of Han nationality,whose families have resided in the northeast area of China for more than 3 generations,were divided into 3 groups: Group 1 (22 cases of type 2 diabetes with maternal inheritance history),Group 2 (34 cases of LADA),Group 3 (23 cases of type 1 diabetes in adolescents).The A3243G of mt DNA was detected in these 79 subjects with the method of PCR RFLP. Results.None of the 79 diabetics studied was positively identified for the A3243G mutation of mt DNA. Conclusion.The A3243G mutation of mt DNA might not be related to the onset of LADA in diabetic population of Han nationality in northeast area of China and there might not be close relationship between A3243G mutation of mt DNA and autoimmunity.