Abstract: The distribution of serum antibody to Legionella pneumophilla type B₁ in the general population of the city of Harbin, Heilongjiang Province was observed.The results showed that the antiboty positivity rate was 4.98% in population of that city and the GMT was 1:1.63. Both the antibody positivity rate and the GMT were not significantly different between two sexes,but both of them increased with the increase in age. Among different professionals, the antibody positivity rate and the GMT were highest in transport, hotal and theater workers and were lowest in office workers.