The outcome of Legionnaires’disease relies mainly on the time laboratory diagnosis is confirmed, allowing initiation of appropriate therapy. We performed and evaluated the current tests for the diagnosis of Legionella infection, in 88 patients presenting with severe community-acquired pneumonia, who had been hospitalized in “Sotiria” Hospital, Athens. We performed detection of the Legionella antigen in sputum by DFA, serology by ELISA and IFA detection of soluble Legionella urinary antigen by ELISA (Biotest EIA) as well as by the new rapid immunochromatographic assay (ICT-Binax OW). Detection of Legionella antigen by DFA gave the poorest positive results (4,3%), while serology and detection of urinary antigen gave almost the same results (6,8%). The main difference was that the detection of urinary antigen was must faster, regardless the methods used, concluding that it has been an important tool for the diagnosis of Legionnaires’disease and should never be neglected. Interestingly, the ICT-Binax NOW seems more practical, because while not lacking sensitivity compared to Biotest EIA, it is much more rapid and simple, while no special equipment or stuff skillfulness. Pneumon 2003, 16(2):173-180.