Sequence-Based Typing (SBT) combined with monoclonal antibody subgrouping of Legionella pneumophila isolates is at present considered the gold standard during epidemiological investigation of Legionnaires' disease outbreaks. In some isolates of L. pneumophila the seventh allele of the standard SBT scheme, neuA, is not amplified because a homolog, refractory to amplification with the standard neuA primers, is present. Consequently a complete seven allele profile, and hence a Sequence Type, cannot be obtained. Subsequently primers were designed to amplify both neuA and the homolog, but these yielded suboptimal sequencing results. In this study novel primers specific for the neuA homolog were designed and internationally validated by members of the ESCMID Study Group for Legionella Infections (ESGLI) at national and regional legionella reference laboratories using a modified version of the online L. pneumophila Sequence Quality Tool. To date the addition of the neuAh target to the SBT protocol allowed full typing data for 108 isolates of 11 different serogroups, namely 1, 2, 3, 4, 5, 6, 7, 8, 10, 13 and 14, which were not previously possible to type using the standard SBT neuA primers. Further studies are necessary to determine why it is still not possible to obtain either a neuA or a neuAh allele from three sg11 isolates. This article is protected by copyright. All rights reserved.