Four hundred and fifty nine isolates of fluorescent pseudomonads were obtained from the leaves and roots of potato plants. Of these, 20 leaf isolates and 28 root isolates induced violacein production in two N-acylhomoserine lactone (AHL)-reporter strains-Chromobacterium violaceum CV026 and VIR24. VIR24 is a new reporter strain for long Nacyl-chain-homoserine lactones, which can not be detected by CV026. Thin-layer chromatography revealed that the isolates produced multiple AHL molecules. We compared the 16S rRNA gene sequences of these isolates with sequences from a known database, and examined phylogenetic relationships. The AHL-producing isolates generally separated into three groups. Group I was mostly composed of leaf isolates, and group III, root isolates. Group II comprised both leaf and root isolates. There was a correlation between the phylogenetic cluster and the AHL molecules produced and some phenotypic characteristics. Our study confirmed that AHL-producing fluorescent pseudomonads could be distinguished in the phyllosphere and rhizosphere of potato plants.