During the past years, human coronaviruses (HCoVs) have been increasingly identified as pathogens associated with more-severe respiratory tract infection (RTI). Diagnostic tests for HCoVs are not frequently used in the routine setting. It is likely that, as a result, the precise role that HCoVs play in RTIs is greatly underestimated. We describe a rapid, sensitive, and highly specific quantitative real-time reverse-transcriptase polymerase chain reaction (RT-PCR) for the detection of HCoV that can easily be implemented in the routine diagnostic setting. HCoV was detected in 28 (11%) of the 261 clinical specimens obtained from patients presenting with symptoms of RTI ranging from common cold to severe pneumonia. Only 1 (0.4%) of the 243 control specimens obtained from patients without symptoms of RTI showed the presence of HCoV. We conclude that HCoVs can be frequently detected in patients presenting with RTI. Real-time RT-PCR provides a tool for large-scale epidemiological studies to further clarify the role that coronavirus infection plays in RTI in humans.