Several strains growing well in minimal media with 500 and 1000 mg/l of oil or phenol as a sole carbon source were isolated from activated sludge purifying petroleum waste waters and identified. Five of the best growing strains classified as Arthrobacter, Pseudomonas, Xanthomonas and Enterobacter were selected and their capacity to remove petroleum components and phenol (in the oil fraction of petrochemical waste waters) was studied. The enzymatic activity of the strains, including respiration intensity and dehydrogenase activity was also determined. All the examined strains were found to use oils as the sole source of carbon (percent age of the oils reduction during cultivation of the individual strains ranged from 58 to 78). Phenol was completely reduced by only one strain. The rest of the strain removed only from 7 to 24% of this compound. The activity of dehydrogenases and the respiration intensity in the presence of the studied substrates -- oil and phenol was low for all the examined strains.