Introduction: Despite common, serious, costly, and often fatal conditions affecting up to 50 % of older patients, delirium is often unrecognized and overlooked. We examine the accuracy of the 4AT for detecting older patients with delirium.Methods: We performed a systematic search of PubMed, Web of Science, PsycINFO, and EMBASE databases from inception to April 2020 and updated to January 2022. Four independently reviewers extracted study data and assessed the methodological quality using the revised quality assessment of diagnostic accuracy studies tool (QUADAS-2). Pooled estimates of sensitivity and specificity were generated using a bivariate random effects model. All statistical analyses were performed with STATA version 15.1 and Meta-DiSc version 1.4 software. Results: Eleven studies with 2789 participants were included. The pooled sensitivity and specificity were 0.87 (95 % CI: 0.81-0.91) and 0.87 (95 % CI: 0.79-0.92), respectively, and the positive and negative likelihood ratios were 6.66 (95 % CI: 4.12-10.74) and 0.15 (95 % CI: 0.10-0.23), respectively. Deeks' test indicated no significant publication bias (t = 0.83, P = 0.43). Univariable meta-regression showed that patient selection and flow and timing significantly influenced the pooled sensitivity (P < 0.05), settings significantly influenced the pooled specificity (P < 0.05).Conclusion: Our meta-analysis demonstrates that 4AT is a sensitive and specific screening tool for delirium in older patients. Its brevity and simplicity support its use in routine clinical practice, particularly in time-poor settings. Clinicians should come to a conclusion based largely on the 4AT findings in conjunction with clinical judgment.