In this study a newly developed Self-rating Inventory for Posttraumatic Stress Disorder (PTSD) is presented. The instrument consists of 47 items, reflecting DSM-III-R criteria, associated features and items corresponding to the disorder of extreme stress not otherwise specified. All items are phrased in a trauma-independent way and are measured on an intensity scale. The instrument was validated on 76 subjects with war-related trauma and 59 psychiatric outpatients, one third of whom were traumatized. Test-retest for the scale was 0.90. The coefficient alpha appeared to be 0.96 for the 47-items scale and 0.92 for the 22 DSM-III-R subscale. The scale correlated significantly with the Clinician Administered PTSD Scale, the Mississippi Scale for Combat-related PTSD, the MMPI PTSD subscale and the Impact of Event Scale. The overall efficiency of the Self-rating Inventory for PTSD was comparable to the overall efficiency of the Mississippi Scale and superior to the MMPI PTSD subscale. Factor analysis on the 22 DSM-III-R items showed 4 factors, representing numbing, intrusion, avoidance and sleeping problems. It is concluded that the Self-rating Inventory for PTSD is a powerful instrument for diagnosing PTSD in survey research. The instrument appears to be capable of differentiating not only between PTSD and non-PTSD subjects but also between traumatized non-PTSD subjects and non-traumatized psychiatric patients.