Objective: To perform a diagnostic accuracy of the rapid ultrasound in shock (RUSH) to diagnose the etiology of undifferentiated shock in patients presenting to the emergency department (ED).Methods: We searched the Medline via PubMed, Scopus, and ISI Web of Knowledge till July 2017. Two independent reviewers screened studies for eligibility. Our study analysis is planned in accordance with the guidelines for meta–analysis of diagnostic studies. In the systematic search, of 397 references, 295 were excluded on the basis of the title and abstract. For the remaining 102 articles, the full text was retrieved and critically reviewed. After the selection process, five papers were included.Results: The pooled estimate of all data showed that the RUSH protocol exhibited high sensitivity (0.87, 95% Confidence Interval (CI): 0.80-0.92, I2 = 46.7%) and specificity (0.98, 95% C. I.: 0.96-0.99, I2 = 30.8%). The AUC for SROC, a global measure of the RUSH protocol performance, was 0.98 ± 0.01, indicates the high accuracy of the test. Positive and negative likelihood ratios reported from the studies ranged from 9.83 to 51.32 and 0.04 to 0.33, respectively. The pooled estimate of all data showed that the RUSH protocol exhibited high positive likelihood ratio (19.19, 95% C. I.: 11.49-32.06, I2 = 14.1%) and low negative likelihood ratio (0.23, 95% C. I.: 0.15-0.34, I2 = 18.4%).Conclusion: This meta-analysis suggests that RUSH protocol has generally good role to distinguish the states of shock in patients with undifferentiated shock referred to the emergency department.