The present invention relates to a pharmaceutical composition useful for the treatment of diseases associated with viruses of the order Nidovirales of the family Coronaviradae, such as Severe Acute Respiratory Syndrome (SARS) viruses in humans and other animals. In particular, this invention relates to a naturally occurring compound, namely, baicalin, extracted and purified from the Chinese medicinal plant Scutellaria baicalensis Georgi (Chinese name: Huang Qin), that exhibits potent antiviral activity against members of the order Nidovirales of the family Coronaviradae that infects humans and other animals; in particular, SARS viruses in humans ("hSARS virus"). The invention also relates to a therapeutic method, using pharmaceutical compositions comprising baicalin compounds, for the treatment, amelioration, management or prevention of diseases associated with members of the order Nidovirales of the family Coronaviradae, such as hSARS.