The report documents a pilot-scale test of a slurry-phase biological reactor for treatment of creosote-contaminated soil. The technology used was a reactor system in which an aqueous slurry of soil was mixed with appropriate nutrients and seeded with micro-organisms to enhance the biodegradation process. In the 12-wk study, a creosote-contaminated soil from the Burlington Northern Superfund Site in Brainerd, MN, was used to test the slurry-phase reactors. The results of a previously-performed bench-scale study were used to optimize a pilot-scale reactor system. Each reactor contained 64 l of 30% slurry (soil: water, w/v). The pilot-scale phase utilized an inoculum of indigenous polynuclear aromatic hydrocarbon (PAH) degraders (9.3 x 10 to the 7th power CFU/g of soil), an inorganic nitrogen supplement in the form of NH4(-N), and a media broth containing potassium, phosphate, magnesium, calcium, and iron. The reduction of total PAHs exceeded 87%. The report presents detailed information concerning the operation, sampling and analysis, and results achieved with the pilot-scale slurry-phase bioremediation system.