Nine Pseudomonas strains, able to degrade polycycle aromatic hydrocarbons (PAHs), were isolated from enriched cultures with naphthalene, as carbon source, and soil samples from a land farming process applied on oil sludge, as inocula. Degradative tests showed that all the strains were capable to catabolize naphthalene (Nah) and phenanthrene (Phn). U2 strain transferred the selected function (Nah) to P. aeruginosa T1 (Hgr Oct+), however some of the transconjugants lost the Oct character, suggesting that it is of plasmidic nature. T1 derivatives as well the wild strains U28 and U31 transferred Nah function to P. putida AC165. All of the examined transconjugants also catabolized phenanthrene, suggesting that Nah and Phn functions in U2, U28, and U31 strains are linked and probably encoded by transferable plasmids.