The feline coronaviruses, members of the family Coronaviridae are enveloped viruses which contain single-strand positive sense RNA. They replicate by a mechanism which results in a high frequency of recombination. Therefore, feline coronaviruses are pathogens of cats exhibiting a spectrum of virulence dependant on the strain. Some strains produce an asymptomatique infection, but others induce an immune-mediated and fatal systemic disease called feline infectious peritonitis (FIP). This paper briefly review the current knowledge about the molecular organization, the replication, the natural immunity and the transmission of feline coronaviruses. The knowledge of the pathogenesis of FIP is still incomplete but can explain the problem encountered to succeed in vaccinating cats against feline infectious peritonitis.