6518 Background: Several studies have demonstrated the importance of pessimism in cardiovascular disease. However, this construct has not been well explored in oncology. Methods: This study examined the survival time of 534 adult who were diagnosed with lung cancer. These patients had completed the Minnesota Multiphasic Personality Inventory (MMPI) approximately 18.2 years prior to their lung cancer diagnosis. MMPI Optimism-Pessimism (PSM) scores were divided into high (60 or more) and low scores (less than 60), and log-rank tests and Kaplan-Meier curves were used to determine survival differences. Multivariate Cox models were used for assessing prognostic values of pessimism along with other known predictors for survival outcome. Results: At the time of diagnosis, patients were on average 67 years old, 48% were female, 85% had non-small cell lung cancer (NSCLC), 15% had small cell lung cancer (SCLC), 30% were stage I, 4% were stage II, 31% were stage III/Limited, and 35% were stage IV/Extensive. Patients who exhibited a non-pessimistic explanatory style survived approximately six months longer than patients classified as pessimists. Pessimists have significantly worse survival rates even after adjusting for other known prognostic variables. Conclusions: Among lung cancer patients, having a pessimistic explanatory style was related to surviving on average six months less compared to patients with a non-pessimistic explanatory style. [Table: see text] No significant financial relationships to disclose.