OBJECTIVE: The authors' objective was to compare the urinary cortisol excretion of Holocaust survivors with posttraumatic stress disorder (PTSD) (N = 22) to that of Holocaust survivors without PTSD (N = 25) and comparison subjects not exposed to the Holocaust (N = 15). METHOD: Twenty-four-hour urine samples were collected, and the following day, subjects were evaluated for the presence and severity of past and current PTSD and other psychiatric conditions. RESULTS: Holocaust survivors with PTSD showed significantly lower mean 24-hour urinary cortisol excretion than the two groups of subjects without PTSD. Multiple correlation analysis revealed a significant relationship between cortisol levels and severity of PTSD that was due to a substantial association with scores on the avoidance subscale. CONCLUSIONS: The present findings replicate the authors' previous observation of low urinary cortisol excretion in combat veterans with PTSD and extend these findings to a non-treatment-seeking civilian group. The results also demonstrate that low cortisol levels are associated with PTSD symptoms of a clinically significant nature, rather than occurring as a result of exposure to trauma per se, and that low cortisol levels may persist for decades following exposure to trauma among individuals with chronic PTSD.