BACKGROUND: Stromal cell-derived factor 1 (SDF1), a potential inhibitor of infection by lymphophilic HIV-1 strains, can help to block the pathway of HIV-1 invasion into the human body.OBJECTIVE: Genotype and polymorphism of SDF1-3 'A allele associated with HIV-1 infection were investigated in She Ethnic Group in the south of China so as explore the possible causes of uninfection by HIV-1 strains among this population.DESIGN: Single sample study.SETTING: Department of Biochemistry and Molecular Biology, Gannan Medical College.PARTICIPANTS: Totally 186 She Ethnic subjects without HIV-1 infection collected randomly from those whose three generations belonged to She Ethnic Group, and inhabited in Qianshan County of Jiangxi Province,Ningde area of Fujian Province and Jingning She County of Zhejiang Province, from January to December 1995.METHODS: The whole blood samples from 186 She Ethnic subjects were collected randomly, and then their genomic DNA samples were extracted respectively. Allelic polymorphism was examined by the polymerase chain reaction and restriction-fragment-length polymorphisms (PCR-RFLP).MAIN OUTCOME MEASURES: The distribution of SDF1-3'A allele in She Ethnic Group in the south of China.RESULTS: The data of 186 She Ethnic subjects entered the result analysis without any loss in the midway. The frequency of SDF1-3 'A allele in She Ethnic Group samples was 19.6%, and the allelic distribution of the gene was in accordance with Hardy-Weinberg equilibrium. No difference was found between male and female individuals.CONCLUSION: The frequency of SDF1-3 'A allele of She Ethnic Group in the south of China was similar to that of Dai Nationality in Yunnan.Based on its slow-down effect on clinical course of AIDS, the mutation of SDF1-3'A is significant in the prevention and treatment of AIDS in She Ethnic Group in the south of China.