Introduction: This study aims to measure the diagnostic accuracy of chest computed tomography (CT) and reverse transcription polymerase chain reaction assay (RT-PCR) in COVID-19 in a systematic review and meta-analysis. Methods: PubMed, Scopus, Embase, and Google Scholar, WHO, SSRN, and MedRxiv have been searched on March 26, 2020 for all the alternative names of the disease and virus. Risk of bias assessment was based on QUADAS-2. Data from English-language studies after January 12, 2019 were pooled to calculate necessary diagnostic values and underwent diagnostic test accuracy, random-effects, proportions, and subgroup meta-analysis. Results: Pooled from 27 included studies, the sensitivity of chest CT was calculated 96.6%, specificity 22.5%, diagnostic odds ratio (DOR) 8.2, positive likelihood ratio (PLR) 1.2 (95% CI: 1.1-1.4), and negative likelihood ratio (NLR) 0.15 (95% CI: 0.1-0.3). The sensitivity for initial RT-PCR was 79.7%, the specificity 100%, and NLR 0.18. Conclusion: Considering the results, in order to diagnose COVID-19 (coronavirus disease 2019), it is recommended to initially performing chest CT to rule out the uninfected people. In suspicious cases, we suggest RT-PCR to confirm the disease. Performing serial RT-PCR instead of the one-time test is highly recommended, to let the viral loads reach the diagnostic levels, especially in cases of high clinical suspicion.