Since discovery of Middle East respiratory syndrome coronavirus (MERS-CoV), a novel betacoronavirus first isolated and characterized in 2012, MERS-CoV real-time reverse transcriptase polymerase chain reaction (rRT-PCR) assays represent one of the most rapidly expanding commercial tests. However, in the absence of extensive evaluations of these assays on positive clinical material of different sources, evaluating their diagnostic effectiveness remains challenging. We describe the diagnostic performance evaluation of 3 common commercial MERS-CoV rRT-PCR assays on a large panel (n = 234) of upper respiratory tract specimens collected during an outbreak episode in Saudi Arabia. Assays were compared to the RealStar (R) MERS-CoV RT-PCR (Alton Diagnostics, Hamburg, Germany) assay as the gold standard. Results showed i) the TIB MolBiol (R) LightMix UpE and Orfl a assays (TIB MolBiol, Berlin, Germany) to be the most sensitive, followed by ii) the Anyplex (TM) Seegene MERS-CoV assay (Seegene, Seoul, Korea), and finally iii) the PrimerDesign (TM) Genesig (R) HCoV_2012 assay (PrimerDesign, England, United Kingdom). We also evaluate a modified protocol for the PrimerDesign (TM) Genesig (R) HCoV_2012 assay. (C) 2017 Elsevier Inc. All rights reserved.