Efforts to improve the efficiency of prolonged exposure (PE) therapy for posttraumatic stress disorder (PTSD) have demonstrated that reducing the length of imaginal exposures does not negatively affect treatment outcome. A recent adaptation of PE, called Concurrent Treatment of PTSD and Substance Use Disorders Using Prolonged Exposure [COPE], integrates substance use disorder treatment with PE in the same timeframe (twelve 90‐minute sessions, 8 of which include imaginal exposure). The current study, which represents a subanalysis of a larger randomized controlled trial, examined how the length of imaginal exposures (nonrandomized and measured continually) related to PTSD, substance use, and depression in a sample of military veterans (N = 31) who completed the COPE treatment. Participants completed an average of 11.5 of the 12 therapy sessions and 7.2 of the 8 imaginal exposures during treatment. Results of 3 linear mixed models indicate that PTSD, substance use, and depressive symptoms all improved over the course of treatment (ps < .001; η2 ranged between .17 and .40), and that the length of imaginal exposures did not significantly interact with any outcome. Although preliminary, the findings suggest that it may be feasible to shorten imaginal exposures without mitigating treatment gains. Implications for treatment are discussed.