A study on the potential applicability of bioaugmentation and biostimulation for a chronically diesel-contaminated site was carried out. The results of the bioaugmentation with diesel-degrading bacteria consortium conveyed the following: with the single strain isolate, JG39 and CF3 along reached the highest degradation; with the consortium that combined the strain(s) with the indigenous, [M + CF3] achieved 100% degradation, followed by [M + 4 strains] and [M + JG39] with ∼ 95% degradability. Either CF3 or JG39 along, or both contemporaneously introducing to the indigenous, is a useful strategy recommended to enhance bioremediation of diesel contamination. LB medium was more advanced than MS medium in culturing the Rhamnolipid (RL) producer P. aeruginosa J4. LB medium, indirectly, helped to stimulate the biomass growth by 3.4 folds over the non-RL-addition after the 84-hr inoculation. The optimal operation condition with the RL addition included using LB medium for culturing the RL producer Pseudomonas aeruginosa J4 and pH value controlling at 7.2. This is an abstract of a paper presented at the 8th International In Situ and On-Site Bioremediation Symposium (Baltimore, MD 6/6-9/2005).