Research suggests that posttraumatic stress disorder (PTSD) is common, debilitating and frequently associated with comorbid health conditions, including poor functioning, and increased health care utilization. This article systematically reviewed the empirical literature on PTSD in primary care settings, focusing on prevalence, detection and correlates. Twenty-seven studies were identified for inclusion. Current PTSD prevalence in primary care patients ranged widely between 2 % to 39 %, with significant heterogeneity in estimates explained by samples with different levels of trauma exposure. Six studies found detection of PTSD by primary care physicians (PCPs) ranged from 0 % to 52 %. Studies examining associations between PTSD and sociodemographic variables yielded equivocal results. High comorbidity was reported between PTSD and other psychiatric disorders including depression and anxiety, and PTSD was associated with functional impairment or disability. Exposure to multiple types of trauma also raised the risk of PTSD. While some studies indicated that primary care patients with PTSD report higher levels of substance and alcohol abuse, somatic symptoms, pain, health complaints, and healthcare utilization, other studies did not find these associations. This review proposes that primary care settings are important for the early detection of PTSD, which can be improved through indicated screening and PCP education.