The recently developed concept Disorder of Extreme Stress Not Otherwise Specified (DES NOS) or complex posttraumatic stress disorder (complex PTSD) is designed to encompass long-standing symptoms not present in PTSD. An exploratory investigation of PTSD and DES NOS was performed with the Structured Clinical Interview for PTSD and for DES NOS in a small sample of Dutch war veterans with combat experience. Both PTSD and DES NOS symptoms were frequently reported. About 67% of the veterans met criteria for PTSD and 38% met criteria for DES NOS. DES NOS appeared to be associated with PTSD. Several DES NOS subcategories proved more important than others for distinguishing "simple" PTSD from complex PTSD.