the expression Medical Geography, more than half a century has been used in the united state including geography concepts and issues related to health and disease. Cancer is a major health problem in the world today, one of the important factors influences its prevalence is environment. Stomach cancer, the prevalence of 9/9%, is the second most common cancer in the world, the province is also the third most common cancer incidence. One of the factors affecting this type of cancer is nitrate in drinking water. In the present study using GIS and mapping software, the epicenter of the outbreak of the disease in the province include the Fereydonshahr City with Age Standardized Rate 55.84, Semirom 54.76, Fereidan 44.21. The sex ratio in gastric cancer patients over a 5-year period from 2006 to 2010 in the province 1.56 is the most common age group suffering from this disease are the age group over 70 years. Finally, to find the relationship between nitrate in drinking water and gastric cancer regression in SPSS and statistical methods were used. It showed a positive correlation coefficient R = 0.42 and P =0.05, And expressed particular attention to the reduction of nitrate in drinking water at the center of this disease and it confirmed the investigation of other factors affecting the incidence of gastric cancer .