Posttraumatic stress disorder (PTSD) is a serious mental health disorder that may not be adequately detected or treated in primary care (PC). The purpose of this study was to compare the clinical characteristics and health care utilization of PTSD patients diagnosed in PC versus in specialty mental health care (MHC) across five large, civilian, not-for-profit healthcare systems. Electronic claims and medical record data on patients treated during 2014 were analyzed. Treatment was considered in terms of initiation and dose (i.e., psychotherapy sessions; pharmacotherapy-prescription psychotropics). Of 5256 patients aged 15-88 with a diagnosis of PTSD, 84.4% were diagnosed by a MHC provider. Patients diagnosed by MHC providers had 4 times the rate of and more enduring psychotherapy than those diagnosed by PC providers. Receipt of psychotropics varied by provider type, with generally higher prescription fill levels for patients in MHC. Strategies to better align patient needs with access and treatment modality in PC settings are needed.