Abstract: More than 3 million persons are injured in work-related accidents in the U.S. annually and posttraumatic stress disorder (PTSD) is a frequent psychological consequence of accidental injuries. While many patients suffering from PTSD respond positively to in vivo or imaginal exposure therapy, patients who experience non-visual flashbacks are particularly difficult to treat. This dissertation analyzed data collected in a prospective study of 80 individuals diagnosed with PTSD after work-related accidental injuries who experienced non-visual flashbacks. Injuries sustained by the participants in this study occurred on the job from industrial machinery, environmental exposure, or motor vehicle accidents. A single licensed psychologist treated all of the participants at the Medical College of Wisconsin. Participants were assessed before treatment, at the end of treatment, at 6-month follow up, and at 12-month follow up. Of the 80 participants, 40 were treated with in vivo exposure and 40 were treated with imaginal exposure. The purpose of this study was to (1) delineate the characteristics of non-visual flashbacks in victims of work-related injuries, and (2) compare the course of treatment and outcomes for in vivo exposure versus imaginal exposure treatment for this unique patient population. Types of non-visual flashbacks experienced by participants included auditory, kinesthetic, olfactory, auditory/kinesthetic, auditory/olfactory, and olfactory/kinesthetic. The results of this study supported the use of imaginal exposure for the treatment of PTSD in individuals with non-visual flashbacks following work-related traumatic injury. Participants treated with both in vivo and imaginal exposure experienced a decrease in symptoms over time. However, participants treated with imaginal exposure experienced more reduction of symptoms than participants treated with in vivo exposure at all assessment times. Positive treatment effects occurred at a greater rate with imaginal exposure than with in vivo exposure treatment. Effects were maintained and continued to improve for many participants at 12-month follow-up. In addition to symptom reduction, clinical improvement measured by return-to-work outcomes occurred at a greater rate for participants treated with imaginal exposure. In addition to statistical findings, three case studies were presented to illustrate unique patterns of change and treatment outcomes.