Complex posttraumatic stress disorder (CPTSD) is characterized in the International Classification of Diseases-11 by affect dysregulation, negative self-concept, and relationship impairments, symptoms also presented in borderline personality disorder (BPD). Some research shows CPTSD as a distinct disorder, others as a subgroup or a replacement for BPD. No review currently amalgamates the findings on whether CPTSD presents too similarly to BPD to be a standalone disorder. This article systematically reviewed similarities and differences in symptom presentations of the two disorders. Six databases were searched (PsycINFO, EMBASE, PubMed, Web of Science, PsycEXTRA, and Open Access Theses and Dissertations) and identified papers were summarized narratively. The majority of studies found distinct profiles for CPTSD and BPD. One study found no differences between the constructs; however, this used a population without severe trauma. CPTSD and BPD can present comorbidly, these individuals will have likely experienced earlier and more frequent interpersonal trauma and display greater functional impairment. (PsycInfo Database Record (c) 2024 APA, all rights reserved).