Duopath Legionella (Merck KGaA, Germany) is a new immunochromatographic assay for the simultaneous identification of cultured Legionella species and L. pneumophila. By testing of 89 L. pneumophila strains and 87 Legionella nonpneumophila strains representing 41 different species, the study provided sensitivity rates for Duopath and a widely used latex agglutination assay of 100% and 98%, respectively, for L. pneumophila, whereas the sensitivity rates differ significantly for Legionella spp. (93% vs. 32%). Using 25 warm shower and pool water samples, Duopath Legionella provided 96% accuracy for L. pneumophila and other Legionella species. Since the ISO standards 11731 and ISO 11731-2 and many country regulations require the identification and confirmation of Legionella spp. in water and environmental samples, the use of Duopath Legionella could contribute to significant less false-negative results. Due to its convenience this assay supports the need for simple phenotypic identification of water isolates. Includes 3 references, tables, figure.