One hundred and twenty three sera of cats were tested by the ELISA method for the presence of antibodies against FeLV antigen. The prevalence rate of infection was 12.1%. The infection was found in clinically ill cats usually over two years of age. There was no significant difference between sexes found in FeLV positive animals. In the group of healthy cats and cats aged up to eight weeks, no antibodies against p. 27 antigen of FeLV were discovered. Besides, it was noted that four of the FeLV positive cats (4 out of 15) were also infected with Hemobartonella felis. Haematological survey revealed that these animals suffered from a more severe anaemia than those infected with H. felis of FeLV alone.