A group of 42 Legionella-like organisms reacting specifically with Legionella spiritensis serogroup 1 antisera were collected throughout Europe by the Centre National de Référence (French National Reference Centre) for Legionella. This group of isolates differed somewhat from L. spiritensis in terms of biochemical reactions, ubiquinone content and protein profile. The latter two analyses revealed that one of these L. spiritensis-like isolates, Turin I no. 1T, was highly related, but not identical to any of the red autofluorescent species of Legionella. In fact, this strain was the first of these particular isolates recognized to emit a red autofluorescence when exposed to UV light. Profile analysis of randomly amplified polymorphic DNA established that the red autofluorescent L. spiritensis-like isolates constituted a homogeneous group distinct from Legionella rubrilucens and Legionella erythra. DNA-DNA hybridization studies involving the use of S1 nuclease confirmed that the indicated group of isolates are a new species of Legionella, for which the name Legionella taurinensis is proposed with strain Turin I no. 1T (deposited as ATCC 700508T) as the type strain.