A phenanthrene- utilizing bacterium was anaerobically isolated and identified as Rhodopseudomonas palustris. It tolerated up to 100 mg phenanthrene l(-1) and degraded 50% of 50 mg phenanthrene l(-1) over 10 days. The presence of phenanthrene caused a prolonged lag phase (2-3 days) in cell growth and affected the photopigments biosynthesis, while DMSO (the solvent for phenanthrene) had no impact on cell growth. The cell surface hydrophobicity of the isolate was also increased.