The present invention relates to a diagnostic assay for the virus causing Severe Acute Respiratory Syndrome (SARS) in humans ("hSARS virus"). In particular, the invention relates to a real-time quantitative PCR assay for the detection of hSARS virus using reverse transcription and polymerase chain reaction. Specifically, the quantitative assay is a TaqMan.RTM. assay using the primers and probes constructed based on the genome of the hSARS virus. The invention further relates to a diagnostic kit that comprises nucleic acid molecules for the detection of the hSARS virus.