Legionella pneumophila is an opportunistic pathogen that replicates within alevolar macrophages resulting in the onset of severe atypical pneumonia. Previously we identified Lpg1905, a eukaryotic-type ecto-nucleoside triphosphate diphosphohydrolase (NTPDase) from L. pneumophila that was required for optimal intracellular replication and virulence and virulence in a mouse lung infection model. In this study, we characterised the activity the activity of a second eukaryotic-type NTPDase, Lpg0971, from L. pneumophila. We observed that recombinant Lpg0971 hydrolysed ATP only and exhibited divalent cation preference for manganese (II) ions. Similar to lpg1905, an lpg0971 mutant carrying pMIP was impaired for replication in both human macrophages and amoebae. However, complementation with either lpg1905 or lpg0971 restored intracellular replication, suggesting functional redundancy between the two enzymes. Unlike many eukaryotic-type proteins from L. pneumophila, neither Lpg1905 nor Lpg0971 were translocated into the host cell by the Dot/Icm type IV secretion system, suggesting that their activity is restricted to the Legionella-containing vacuole. In summary, the ability of L. pneumophila to replicate in eukaryotic cells relies in part on the ability of the pathogen to hydrolyse ATP within an intracellular compartment.