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Prompt detection of Legionella pneumophila is essential for rapid investigation of legionellosis. Furthermore, as the majority of L. pneumophila infections are caused by serogroup 1 (sg1) strains, rapid identification of such strains can be critical in both routine and outbreak scenarios. The ESCMID Study Group for Legionella Infections (ESGLI) was established in 2012 and immediately identified as a priority the validation of a reliable, easy to perform and interpret, cost-effective qPCR assay to standardise the detection of L. pneumophila DNA amongst members. A novel L. pneumophila assay targeting the mip gene was designed and combined with previously published methodologies amplifying the sg1 marker ( wzm) and the green fluorescent protein gene ( gfp) internal process control. The resulting triplex assay was validated internationally on the three qPCR platforms used by the majority of European Legionella reference laboratories: ABI 7500 (Life Technologies), LightCycler 480 Instrument II (Roche) and Rotor-Gene Q (Qiagen). Clinical and EQA specimens were tested together with a large panel of strains (251 in total) to validate the assay. The assay proved to be 100 % specific for L. pneumophila and sg1 DNA both in silico and in vitro. Efficiency values for mip and wzm assays ranged between 91.97 and 97.69 %. Limit of detection values estimated with 95 % confidence were adopted for mip and wzm assays on all three qPCR platforms. Inhibition was not observed. This study describes a robust assay that could be widely implemented to standardise the molecular detection of L. pneumophila among ESGLI laboratories and beyond. [ABSTRACT FROM AUTHOR]