Background: Identifyng the incidence of cancer helps in planning and prioritizing resources for its screening, prevention, treatment and diagnosis. This study aimed at investigating a 25-year trend in gastrointestinal cancer in Northern Iran in the time span of 1991-2016. Methods: This research was a trend analysis. Study population was one thousand five hundred and thirty-five cancer patients referring to Shahid Rajai Hospital in Babolsar, northern Iran, as the only center for radiotherapy in the North of Iran, during 1991-2016. Results: The highest incidence of stomach cancer was 111 (35) in 2011 and the lowest incidence was 44 (16.3) in 1996, The highest frequency of esophageal cancer was reported 137(56.1) cases in 1991 and the lowest frequency was 78 (26.3) cases in 2016, while the highest incidence of colorectal cancer was 109 (36.7) cases in 2016 and its lowest frequency was 32 (16.3) in 1996. There was also a significant difference in the frequency of gastrointestinal cancers in different studied years (p <.001). Conclusions: The trends in the incidence of stomach and colorectal cancers in northern Iran were increasing and esophageal cancer was decreasing.  
