Despite the substantial disease burden of anxiety disorders, physicians have a poor understanding of factors that predict their typical persistent course. This systematic review of predictors of persistent anxiety disorders covered 48 studies with 29 690 patients diagnosed with an anxiety disorder that were published in PubMed, PsycINFO, and Web of Science between Jan 1, 1980 (introduction of DSM-III), and Dec 1, 2019. We also compared predictors between children, adolescents, adults, and older adults (ie, ≥55 years). A persistent course was primarily predicted by clinical and psychological characteristics, including having panic attacks, co-occurring personality disorders, treatment seeking, poor clinical status after treatment, higher severity and longer duration of avoidance behaviour, low extraversion, higher anxiety sensitivity, and higher behavioural inhibition. Unlike disorder onset, sociodemographic characteristics did not predict persistence. Our results outline a profile of patients with specific clinical and psychological characteristics who are particularly vulnerable to anxiety disorder persistence. Clinically, these patients probably deserve additional or more intensive treatment to prevent development of chronicity.