Objective To investigate Helicobacter pylori(Hp)infection and HLA-DQA1 allelic frequency in family members of children with recurrent abdominal pain.Methods One hundred and eighteen family members of 20 children with recurrent abdominal pain were divided into two groups:with and without recurrent abdominal pain.Serum Hp antibody was tested by dot immunogold filtration assay and immunophenotyping was determined by Western blot(immunobiot)technique.Polymerase chain reactionsequence specific primers(PCR-SSP)technique Was applied to identify HLA-DQAi allelic frequencies.Hardy-Weinberg equilibrium test was performed(P>0.05),and Chi-square test was used to compare the frequency of HLA-DQA1 alleles between the groups.Results The Hp seropositive rate in 118 members Was 100%and the Hp immunophenotyping was 96.6%.The prevalence of Hp Ⅰ and Ⅱ type was 55.1%(65/118)and41.5%(49/118).HLA-DQA1*0302 allelic frequency Was significantly higher in subjects with recurrent abdominal pain than that in subjects without one(23%vs.2%,X2=13.277,P=0.000).Conclusion There is immunogenetic difference between familial members with and without recurrent abdominal pain infected by Hp,and HLA-DQA1*0302 may be the associated gene contributing to different clinical outcomes after Hp infections.