This review aims to summarize current data describing the characteristics of bovine coronavirus (BCV) and the three clinical syndromes with which this virus is associated. The first half of this paper consists of a general description of the virus, commencing with a brief outline of the methods used for in vitro growth. The structure of the virus is then described in more detail, with particular reference to the structure and functions of the four major viral proteins. This is followed by an outline of the unique replication strategy adopted by coronaviruses. The second half of this review discusses the clinical significance of the virus, beginning with a detailed account of BCV-induced neonatal calf diarrhoea, the clinical syndrome with which this virus is most commonly associated. The clinical and epidemiological importance of BCV respiratory tract infection is then discussed, and finally the evidence supporting the aetiological role of BCV in outbreaks of winter dysentery in adult cattle is examined.