Legionella species, which are fastidious and ubiquitous worldwide in natural water environment such as rivers, lakes and artificial water systems, are the causative agents of Legionnaire’s disease. Legionella pneumophila is the most important human pathogen, followed by L. micdadei, L. longbeachae, L. dumoffii, and other rare species. Accurate identification of Legionella spp. other than L. pneumophila is difficult because of biochemical inertness and phenotypic identity of different species. Clinical manifestations caused by Legionella infection are usually indistinguishable from pneumonia caused by other bacterial pathogens. Since the symptoms are nontypical, it is difficult clinically to identify the actual causative agent. Therefore, the rapid and accurate identification of Legionella species have been of increasingly important. DNA microarray technology displays a high potential in the testing and analysis of environmental samples. The feasibility of using an oligonucleotide array for identification of 18 species of Legionella was evaluated in this study. The method consisted of PCR amplification of the macrophage infectivity potentiator (mip) gene, followed by hybridization of the digoxigenin-labeled PCR products to a panel of 37 oligonucleotide probes (16-27 nucleotides) immobilized on a nylon membrane. A collection of 51 target strains (18 species) and 71 nontarget strains (62 species) were analyzed by the array. Both the sensitivity (51/51 strains) and specificity (71/71 strains) of the array were 100%. The detection limit of the array was 10 pg (L. micdadei ATCC 33218T, L. pneumophila ATCC 33152T) of genomic DNA per assay. The array was also used to directly detect Legionella spp. in water samples, and a detection rate of 12.0% (6/50) was obtained. The array method is reliable and can be used as an accurate alternative to conventional or other molecular methods for identification of Legionella spp..