Introduction: Improvement in posttraumatic stress disorder (PTSD) is associated with better health behavior such as better medication adherence and greater use of nutrition and weight loss programs. However, it is not known if reducing PTSD severity is associated with smoking cessation, a poor health behavior common in patients with PTSD. Aims and Methods: Veterans Health Affairs (VHA) medical record data (2008-2015) were used to identify patients with PTSD diagnosed in specialty care. Clinically meaningful PTSD improvement was defined as ≥20 point PTSD Checklist (PCL) decrease from the first PCL ≥50 and the last available PCL within 12 months and at least 8 weeks later. The association between clinically meaningful PTSD improvement and smoking cessation within 2 years after baseline among 449 smokers was estimated in Cox proportional hazard models. Entropy balancing controlled for confounding. Results: On average, patients were 39.4 (SD = 12.9) years of age, 86.6% were male and 71.5% were white. We observed clinically meaningful PTSD improvement in 19.8% of participants. Overall, 19.4% quit smoking in year 1 and 16.6% in year 2. More patients with versus without clinically meaningful PTSD improvement stopped smoking (n = 36, cumulative incidence = 40.5% vs. 111, cumulative incidence = 30.8%, respectively). After controlling for confounding, patients with versus without clinically meaningful PTSD improvement were more likely to stop smoking within 2 years (hazard ratio = 1.57; 95% confidence interval: 1.04-2.36). Conclusions: Patients with clinically meaningful PTSD improvement were significantly more likely to stop smoking. Further research should determine if targeted interventions are needed or whether improvement in PTSD symptoms is sufficient to enable smoking cessation. Implications: Patients with PTSD are more likely to develop chronic health conditions such as heart disease and diabetes. Poor health behaviors, including smoking, partly explain the risk for chronic disease in this patient population. Our results demonstrate that clinically meaningful PTSD improvement is followed by greater likelihood of smoking cessation. Thus, PTSD treatment may enable healthier behaviors and reduce risk for smoking-related disease.