Deoxyribonucleic acid relatedness studies (S1 nuclease method) have shown that 15 strains isolated from three Lebanese spring waters, belonging to the genus Pseudomonas, formed two homogeneous DNA groups, with a within-group DNA relatedness ranging from 70 to 100%. These groups are referred to as Pseudomonas cedrella sp. nov. and Pseudomonas orientalis sp.nov. These strains were previously grouped on the basis of a numerical analysis in phenons Ve, Vd, Vg, and VI. DNA relatedness with 65 strains representing 24 species of the genus Pseudomonas sensu stricto was below 50%. The highest DNA binding value (50%) was found with P. marginalis species. A comparison of the complete 16S rRNA gene sequences of the strains representing the two new deoxyribonucleic acid hybridization groups, i.e., strains CFML 96-198T and CFML 96-170T, and the sequence of other strains of the genus Pseudomonas revealed that these strains (CFML 96-198T and CFML 96-170T) fell within the 'Pseudomonas fluorescens intrageneric cluster'. The G+C contents of the DNA of P. cedrella CIP 105541T and P. orientalis CIP 105540T were 59 and 60 mol%, respectively. The two species can be differentiated from each other by the fact that P. cedrella strains hydrolyze erythritol and D-lyxose. P. cedrella grouped together a total of nine strains from phenotypic groups Ve, Vg, and VI. P. orientalis grouped together six strains from both phenotypic groups Vd and Ve.