Patients with posttraumatic stress disorder (PTSD) who fail to respond to established treatments are at risk for chronic disability and distress. Although treatment-resistant PTSD (TR-PTSD) is a common clinical problem, there is currently no standard method for evaluating previous treatment outcomes. Development of a tool that could quantify the degree of resistance to previously provided treatments would inform research in patients with PTSD. We conducted a systematic review of PTSD treatment trials to identify medication and psychotherapy interventions proven to be efficacious for PTSD. We then developed a semi-structured clinician interview called the Emory Treatment Resistance Interview for PTSD (E-TRIP). The E-TRIP includes clinician-administered questions to assess the adequacy and benefit derived from past treatment trials. For each adequately delivered treatment to which the patient failed to respond, a score is assigned depending on the strength of evidence supporting the treatment's efficacy. The E-TRIP provides a comprehensive assessment of prior PTSD treatments that should prove valuable for researchers studying TR-PTSD and evaluating the efficacy of new treatments for patients with PTSD. The E-TRIP is not intended to guide treatment; rather, the tool quantifies the level of treatment resistance in patients with PTSD in order to standardize TR-PTSD in the research domain.