The Feline Infectious Peritonitis (FIP)-virus causes a severe disease with high mortality in cats. Many experiments were attempted to produce a vaccine against FIP. The most experimental vaccines gave no protection against an infection with FIP-virus or they led to a quicker disease. Recently a first vaccine is available for the practice and for application. It contains a sensitive to temperature strain of the FIP-virus for intranasal instillation. The efficacy was demonstrated under experimental conditions. Results of field tests about the efficacy are unknown up to now. The harmlessness of the vaccine was tested in practice.