aim: the aim of the present study was the assessment of association of helicobacter pylori of dental plaque and stomach in a more homogenous population and also to determine the diagnostic value of dental plaque for gastric infection. materials and methods: based on the results of rapid urease test (rut) on specimens from gastric antrum, 88 patients with symptoms of dyspepsia were assigned into two groups of infected and non-infected with helicobacter pylori. supragingival plaque samples were collected from mandibular first and second molar area using and sterile curette and were investigated using rut. statistical analysis of data was performed using chi-square test and independent t-test. results: h.pylori was detected in 34.1 % of dental plaque specimens. the prevalence of helicobacter pylori infection in dental was 31.8 % and 36.4 % in patients with and without gastric infection (p=0.6). also the interaction of age and infection was not significant but the prevalence of h. pylori both in the dental plaque and the stomach of male patients was higher than female patients. conclusion: there is not any significant association between the helicobacter pylori of the dental plaque and the stomach. also the dental plaque can not be used as a primary diagnostic aid for gastric infection.