Opportunistic screening for lung cancer is commonly conducted in Korea in accordance with physicianrecommendations and screenee’s preferences. However, studies have yet to thoroughly examine the public’sunderstanding of the risks posed by lung cancer screening. This study was conducted to assess changes inintentions to undergo lung cancer screening in response to being informed about exposure to radiation duringlow-dose computed tomography (LDCT) tests and to identify factors with the greatest influence thereonamong Korean men. We conducted sub-group interviews among men chosen from the 2013 Korea NationalCancer Screening Survey (KNCSS), a nationwide, population-based, cross-sectional survey of men aged 40 to74 years and women aged 30 to 74 years. From 4100 participants in the KNCSS, 414 men who underwent anycancer screening test within the last 2 years were randomly selected for inclusion in this study. Via face-to-faceinterviews, their intentions to undergo lung cancer screening were assessed before and after being informedabout exposure to radiation during LDCT testing. Of the 414 participants, 50% were current smokers. Afterreceiving information on the benefits of the test, 95.1% stated an intention to undergo screening; this decreasedto 81.6% after they received information on the harms of the test. The average decrease in intention rate was35.3%. Smoking status, household income, and education level were not associated with lowered intentions toundergo lung cancer screening. Participants who were older than 60 years old (OR=0.56; 95% CI= 0.33-0.96)and those with less concern for radiation exposure (OR=0.56; 95% CI=0.36-0.89) were less likely to lower theirscreening intentions. The results of this study suggest that there is a need to educate both non-smokers andformer smokers on the harms of lung cancer screening.