 To achieve these objectives, we propose to conduct a Phase IIa, multi-site, double-blind, placebo controlled trial of mifepristone in veteran outpatients with military-related PTSD through the VAs Cooperative Clinical Trial Award program. We propose to enroll 136 unmedicated male veterans with military related PTSD at four VA sites Albuquerque, NM, Bronx, NY, Durham, NC, and San Diego, CA. Eligible veterans will be randomly assigned in parallel groups to treatment with 600 mgday mifepristone or placebo for one week and followed for up to three months. Using statistical selection theory, we propose to determine whether 600 mg of mifepristone yields a sufficiently high proportion of clinical responders after one month to warrant more extensive and definitive research as part of a Phase III trial. Secondarily, we seek to determine the effect of the dose of mifepristone compared to placebo on the trajectory of CAPS scores and the time to addition of rescue medication, as well as compare rates of adverse events and serious adverse events across the three groups. We will also describe the effects of mifepristone on several other clinical parameters including PTSD symptomology, depression severity, sleep quality, and functional impairment. Several measures of neuroendocrine functioning will also be obtained to explore the relationship of plasma cortisol and ACTH levels to clinical response and the time to addition of rescue medications. 