Legionella pneumophila serogroup 1 occurrence has been investigated in 168 hot water samples from 24 hotels, situated in 6 counties in İzmir province of Turkey, from 15 June to 30 September of the year 2000. Sampling was carried out at 15-day intervals and seven samples were taken from each of the hotels' hot water reservoirs and hot water networks. The samples were (1 L) concentrated using polycarbonate filters (mesh size 0.22 μm). Isolation was achieved using selective medium, GVPC agar. The samples were concentrated by membrane filtration, divided into three portions and cultured without pretreatment, after acid treatment, and after heat treatment, on GVPC agar. One hundred and ten isolates were identified as L. pneumophila sg 1 using the Legionella Latex Test (Oxoid). Arbitrarily primed PCR (AP PCR) was employed to assess the clonal relationship between Legionella pneumophila sg 1 isolates from the hot water samples of the hotels. Three genotypes of L. pneumophila sg 1 isolates were identified. With a high prevalence of type A, 22 hotels were found to be colonized with L. pneumophila serogroup 1, while only 2 were free from the bacteria. [ABSTRACT FROM AUTHOR]