Compositions are disclosed as nucleic acid sequences that may be used as amplification oligomers, including primers, and detection probes that hybridize specifically to Legionella pneumophila 23S rRNA sequences or DNA encoding 23S rRNA. Reaction mixtures are disclosed that contain oligonucleotides for the in vitro amplification and/or detection of Legionella pneumophila 23S rRNA sequences or DNA encoding 23S rRNA. Methods are disclosed for amplifying and/or detecting the presence of L. pnuemophila in samples by using the disclosed compositions in in vitro methods that include nucleic acid amplification and/or detection of a 23S rRNA sequence or DNA encoding the 23S rRNA sequence to produce a detectable amplification product. Reaction mixtures are disclosed that contain oligonucleotides for the in vitro amplification and/or detection of Legionella pneumophila 23S rRNA sequences or DNA encoding 23S rRNA.