Background: The purpose of this study was, to investigate prefrontal cortex (PFC) volumes in youth with posttraumatic stress symptoms (PTSS) and explore the relationship between cortisol secretion and PFC volumes.Methods: Total brain tissue volumes, segmented areas of the PFC, and diurnal cortisol secretion were examined in a sample of 33 youth aged 10 to 16 years. Cerebral volumes were available fors 45 subjects (30 PTSS and 15 control subjects).Results: Youth with PTSS had significantly decreased total brain tissue and total cerebral gray volumes in comparison with healthy control subjects. While controlling for total cerebral gray volume, the PTSS group demonstrated decreased left ventral and left inferior prefrontal gray volumes. A significant negative association was found between prebedtime cortisol levels and left ventral PFC gray volumes for the full sample.Conclusions: Findings suggest associations between posttraumatic stress and PFC neurodevelopment. Findings also suggest a link between PFC development and cortisol secretion.