Feline infectious peritonitis is a viral disease caused by a mutated strain of feline coronavirus. The disease usually develops in cats in kennels, shelters, temporary shelters and more densely populated free groups of cats. The frequency is significantly higher among kittens and young cats. Mortality is extremely high once clinical signs appear. The virulence and infectious dose depend on the virus type and strain. Sick and infected animals, persistent carriers, contaminated litter trays, bowls and combs may be the source of infection. The virus is transmitted by indirect contact. Faeces contain FCoV at high concentrations, and the faecooral route of transmission is most important. The incubation period is from 2 to 3 weeks up to a few months, and sometimes years, depending on the immunological status of the animal. Two different forms of disease have been distinguished: effusive (wet form) and non-effusive (dry form). The wet form is characterized by the accumulation of fluid in the body cavities, and the dry form with granulomatous infiltration of the parenchymal organs and intestines. Pathoanatomical and histological changes show that it is most often a combination of wet and dry forms of the disease. A reliable diagnosis is possible only by post mortem pathohistological finding, which is considered the gold standard in the diagnosis of this disease. Treatment of feline infectious peritonitis involves only symptomatic therapy of the disease, as opposed to treating the cause. Feline coronavirus is widespread in a multi-cat environment and it is difficult to minimize the risk of spread of the infection. Vaccination is not routinely used in practice.