INTRODUCTION:: Previous research on smoking withdrawal in posttraumatic stress disorder (PTSD) has been limited by the use of retrospective and observational methods and has lacked repeated assessments on the first day of abstinence and evaluation of the conditioned effects of smoking. METHODS:: Smokers with (n = 17; 59% female) and without (n = 30; 17% female) PTSD completed 3 randomly ordered experimental sessions using a 2 (group: PTSD vs. non-PTSD) × 3 (smoking condition: usual brand vs. nicotine free vs. no smoking) design. Before the smoking manipulation, participants completed self-report measures of smoking urges and withdrawal, followed by withdrawal assessment after the smoking manipulation. RESULTS:: Compared with smokers without PTSD, smokers with PTSD exhibited higher craving ((Equation is included in full-text article.)= 16.60, p < .001) and habit withdrawal ((Equation is included in full-text article.)= 10.38, p = .001) following overnight abstinence. PTSD smokers also exhibited worsening negative affect throughout the morning when not smoking a cigarette ((Equation is included in full-text article.)= 11.30, p = .004). After smoking, smokers with PTSD reported diminished relief from craving ((Equation is included in full-text article.)= 6.49, p = .011), negative affect ((Equation is included in full-text article.)= 4.51, p = .034), arousal ((Equation is included in full-text article.)= 6.46, p = .011), and habit withdrawal ((Equation is included in full-text article.)= 7.22, p = .007), relative to smokers without PTSD. CONCLUSIONS:: Results of this preliminary investigation suggested that after overnight abstinence, PTSD smokers experienced worse withdrawal symptoms and greater urges to smoke for both positive and negative reinforcement. Research on smoking withdrawal early in the course of smoking abstinence in PTSD could inform interventions targeting abstinence early in the quit attempt.