Gastric cancer (GC) is the fifth most common cancer in the world, with a wide variation in incidence ratesacross different geographical areas. In Iran GC is the most common cancer in males and it is reported to bethe third most prevalent after breast and colorectal in females. A geographical information system (GIS) allowsinvestigation of the geographical distribution of diseases. The purpose of the present study was to explore therelationship between gastric cancer and effective climatic factors using GIS. The dispersion distribution andthe relationship between environmental factors effective on cancer were measured using Arc GIS. Of all cases,672 (73.8%) were in males with a sex ratio of 3 to1. The highest incidence by cities was seen in Namin with 137.5per 100,000. The results of this study showed that the distribution of GC around the Sabalan volcanic mountainwas significantly higher than other places in the same province. These results can be considered as a window tofuture comprehensive research on gastric cancer.