Helicobacter pylori has been associated with gastritis, peptic ulcer, and gastric adenocarcinoma. The clinical outcome of Helicobacter pylori infection may be associated with or without CagA.  To investigate presence of CagA gene in Helicobacter pylori strains among patient sera  about 100 serum specimens that were positive were taken. serum samples were studied using unique primers, CagA gene was investigated among the H.pylori strains. Among tested  samples, cagA genome was detected in 15. PCR method was done on serum  positive samples and  were found that the prevalence of CagA gene in  patient sera  were 18% (18 from 100 cases ). According to the findings, it is suggested that presence of CagA gene in strains of Helicobacter pylori may play an important role in aggrevating disorders.In this investigation for first time in world we enable detect cagA genome in patient sera. H. pylori dont create  bacteremia and septicemaia but enable secret CagA protein and genome to host celles. Thus risk of integration of cagA genom in host cell  chromosome  and induction of antibodies against it to exist.