Objective.To identify the A3243G mutation of mi tochondrial（mt ）DNA in patients with latent autoimmu ne diabetes mellitus in adults（LADA）of Han nationality in the northeast a rea of China.Methods.Seventy-nine diabetics of Han natio nality

whose families have resided in the northeast area of China for more than 3generations

we re divided into 3groups:Group 1（22cases of type 2diabetes with mater-nal inheritance history）

Group 2（34cases of LADA）

Group 3（23cases of type 1diabetes in adolesc ents）.The A3243G of mt DNA was detected in th ese 79subjects with the method of PCR-RFLP.Results.None of the 79diabetics studied was p ositively 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 dia betic popula-tion of Han nationality in northeast area of China and there might not be close relationship between A3243G mut a-tion of mt DNA and autoimmunity.