Legionellosis is a notified disease in Poland since 2001, but laboratory diagnostic methods were introduced even earlier, in 1997. In 2005 the 21 cases of legionellosis were reported in Poland, the incidence rate was 0.055 /100,000. The increasing trend in incidence rate was due to an active cooperation with some hospital staff and financial support from Polish Committee of Research Activity. All cases were laboratory diagnosed in National Institute of Hygiene, the only place where laboratory tests are performed. Most of the cases were diagnosed with serological tests -determination with ELISA test the anti-legionella antibodies in IgM fraction as the most recent reaction for Legionella infection, few by detection of legionella antigen in urine. All BAL specimens from several patients were negative when examined with culture method, but some were positive with PCR only. Since 1987 to 2005 the 15 foreign tourists were registered in EU countries as probably infected in Poland. Epidemiological investigation with the examination of water system for Legionella sp., cleaning and disinfection (if needed) was done in suspected hotels.