Legionnaires disease is a severe from of pneumonia caused by Legionella species which arc ubiquitious in both natural and man-made environments. It has high morbidity and case fetality rates. The disease is acquired by aspiration of water or inhalation of aerosols containing the bactena from environmental sources. Early diagnosis and appropriate treatment are important factors in determining prognosis. Clinical and laboratory predictors will not reliably identify cases of legionnaires disease, therefore the diagnosis of Legionnaires' disease requires specific diagnostic tests. The diagnosis of Legionnaires' disease is made by culture, Legionella urinary antigenaria, polymeras ion, or serologic analyses. Isolation of Legionella from clinical samples is the gold standart for diagnosing Legioimaire's disease. Legionella urinary antigen tests are easy and useful for early diagnosis of Legionnaires' disease. Flouroquinolones, macrolides and doxycicline are drugs of choice. Legionnaires' disease is considered a preventable illness since it is possible to control and remove the bacteria in reserviors. In Turkey, travel-associated Legionnaires' disease has a specific surveillance programe since 1996. After the year of 2015, it became mandatory to take environmental cultures for Legionella from the hospital water systems. The aim of this review is to raise awereness for legionollosis and to summarize the current literature.