Abstract Background: The potential for negative screening to reduce smoking cessation and long-term abstinence is a concern in lung cancer screening. We examine whether consistently negative results during long-term participation in a lung cancer screening program reduce cessation or increase relapse. Methods: Participants (N = 2,078) in the Early Lung Cancer Action Program received annual screenings and periodic smoking behavior surveys over a follow-up period as long as 12 years. Point abstinence and prolonged abstinence were examined among 730 baseline smokers. Relapse was examined among 1,227 former smokers who quit for 1 year or more at enrollment, 121 recent quitters at enrollment, and 155 baseline smokers who quit during follow-up. Abstinence and relapse for participants with consistently negative computerized tomography scan results were compared with those with non-cancer–positive results using stratified Cox models. Results: Baseline smokers with negative computerized tomography scans had a 28% lower likelihood of achieving point abstinence at one or more follow-up assessments compared with those with positive scans (hazard ratio, 0.72; P < 0.0004), but consistently negative scans were not associated with a lower likelihood of prolonged abstinence. A consistently negative scan was not associated with a higher likelihood of relapse back to smoking for long-term former smokers, recent quitters, or those who quit during follow-up. Conclusions: We did not detect a lower long-term smoking abstinence or increased relapse over a 6-year period of follow-up among individuals participating in a lung cancer screening program who have a consistently negative screening compared with those with a positive, but noncancer, screening result. (Cancer Epidemiol Biomarkers Prev 2009;18(12):3476–83)