The severe acute respiratory syndrome (SARS) is an emerging and highly contagious infection caused by a newly discovered strain of coronavirus.1 Since the clinical case definition of SARS is similar to other severe atypical pneumonias, specific laboratory tests that can accurately diagnose SARS-associated coronavirus (SARS-CoV) infection are important. However, published data are insufficient to investigate whether clinically diagnosed SARS patients may include some non-SARS pneumonia. Therefore, we aimed to determine clinical and laboratory features to differentiate SARS patients from non-SARS pneumonias that could reduce misdiagnosis of SARS. A retrospective analysis of clinical and laboratory characteristics after the initial onset of SARS, as well as its convalescent-phase, was examined from clinically diagnosed 197 SARS patients.