Few studies have examined the relationship between social support and stages of adoption of cancer screening.Here we investigated associations between both structural and functional aspects of social support and stagesof adoption of gastric cancer screening in the general population of Korea. The study population was derivedfrom the 2011 Korean National Cancer Screening Survey (KNCSS), an annual cross-sectional survey that usesnationally representative random sampling to investigate cancer screening rates. Data were analyzed from3,477 randomly selected respondents aged 40-74 years. Respondents were classified according to their stage ofadoption of gastric cancer screening: precontemplation (13.2%), contemplation (18.0%), action/maintenance(56.1%), relapse risk (8.5%), and relapse stage (4.1%). Respondents with larger social networks were more likelyto be in the contemplation/action/maintenance, or the relapse risk/relapse stages versus the precontemplationstage (OR=1.91, 95%CI: 1.52-2.91; p for tend=0.025). Emotional and instrumental supports were not associatedwith any stage of adoption of gastric cancer screening. However, respondents who reported receiving sufficientinformational support were more likely to be in the relapse risk/relapse stages versus the precontemplation, orthe contemplation/action/maintenance stage (p for trend=0.016). Interventions involving interactions betweensocial network members could play an important role in increasing participation in gastric cancer screening.