Serological examinations with the use of IMPA of 335 cats not vaccinated against infectious feline rhinotracheitis (FRT) showed a prevalence of feline herpesvirus type 1 (FHV-1) in 61.5% of Polish cats. Most of the seropositive cats had high (16-64) or very high (128-512) FHV-1 antibody titre. The seropositive cats were mainly detected in large towns or animal shelters (82% seropositive animals). Most seropositive cats were more than 12 months old. The lowest percentage of FHV-1 seropositive animals was noted in cats less than 3 months old. IMPA can be used for the routine serological diagnosis of herpesvirus infections in cats.