Five typing methods were evaluated, utilising 63 strains of fluorescent pseudomonads, to assess their usefulness as tools to study the bacterial diversity within this complex group. The methods used were Biolog metabolic profiling, restriction fragment length polymorphism ribotyping, PCR ribotyping, and repetitive element sequence-based PCR (rep-PCR) utilising BOX and enterobacterial repetitive intergenic consensus (ERIC) primers. Cluster analysis of the results clearly demonstrated the considerable homogeneity of Pseudomonas aeruginosa isolates and, conversely, the heterogeneity within the other species, in particular P. putida and P. fluorescens, which need further taxonomic investigation. Biolog metabolic profiling enabled the best differentiation among the species. Rep-PCR proved to be highly discriminatory, more so than the other DNA fingerprinting techniques, demonstrating its suitability for the analysis of highly clonal isolates. RFLP ribotyping, PCR ribotyping, and rep-PCR produced specific clusters of P. aeruginosa isolates, which corresponded to their origins of isolation, hence we recommend these methods for intraspecific typing of bacteria.