Aims: Biofilm formation and polycyclic aromatic hydrocarbons (PAHs) degradation by a marine bacterium Stenotrophomonas acidaminihila NCW-702 was investigated. Methods and Results: The biofilm structure was studied by confocal laser scanning microscopy (CLSM). Both planktonic and biofilm cultures were used for PAHs (phenanthrene and pyrene) degradation. In 7 days, Sten. acidaminiphila biofilm culture efficiently degraded 71.1 +/- 3.1% and 40.2 +/- 2.4% of phenanthrene and pyrene, respectively, whereas 38.7 +/- 2.5% of phenanthrene and 29.7 +/- 1% of pyrene degradation was observed in planktonic culture. The presence of phenolic intermediates in the culture supernatant during degradation process was evaluated by Folin-Ciocalteu reagent. The average thickness and diffusion distance of Sten. acidaminiphila NCW-702 biofilm was found to be 23.94 +/- 2.62 mu m and 2.68 +/- 0.7 mu m, respectively. Bacterial biofilms have numerous metabolic features that aid in the degradation of hydrophobic organic pollutants. Conclusions: Biofilm of Sten. acidaminiphila NCW-702 was able to degrade PAHs more efficiently as compared to planktonic cells. The findings support the efficacy of biofilms over planktonic culture in bioremediation applications. Significance and Impact of the Study: The study provides a constructive application of bacterial biofilms for the bioremediation of hydrophobic organic contaminants. The biofilm mode remediation process has the advantage of reusability of bacterial biomass and is also a low cost process as compared to cell immobilization techniques.