The comparative treatment efficiency of eye movement desensitization and reprocessing (EMDR) therapy and prolonged exposure (PE) therapy for the treatment of posttraumatic stress disorder (PTSD) was tested for 20 participants diagnosed with PTSD. Efficiency was operationalized as the total exposure time to traumatic memories during and between sessions; the number of trauma memories processed over the course of therapy; how many sessions were required to resolve the primary trauma; and lower subjective units of disturbance (SUD) levels after the initial treatment session. Participants were randomized to each condition and received 12 90-minute sessions of therapy over 6 weeks. Symptoms were assessed by treatment-blind assessors at posttreatment, and at 3 and 6 months follow-up. Results demonstrated a significant decrease in symptoms posttreatment for PTSD (d =.64), depression (d =.46), anxiety (d =.52) and stress (d =.57) for both groups, which was maintained at 3 months. At 6 months there was a small increase in symptoms compared to the 3-month time point on the Clinician-Administered PTSD Scale (CAPS) but no significant change in any self-report symptoms EMDR was significantly more efficient than PE. EMDR participants had less total exposure time to traumatic memories when homework hours were included (d =.66), reported lower SUD scores after the first session (d =.45), required fewer sessions for the target memory to decrease to near zero distress levels (d =.84), and processed more traumatic memories.