In the summer of 1989, EPA and Exxon Corp. conducted a joint field study to determine if natural biodegradation of the Prudoe Bay crude oil spilled from the Exxon Valdez could be accelerated by application of oleophilic and water soluble fertilizers. Numerous private firms have since submitted proposals to have their microbial products tested for bioremediation enhancement. EPA commissioned the National Environmental Technology Applications Corporation (NETAC) to coordinate an effort to select and test commercial products for efficacy against Alaskan crude oil. A panel of experts was assembled to review the proposals, and nine products were selected for the first tier of testing. The experiments were conducted at the Risk Reduction Engineering Laboratory in Cincinnati. Three lines of evidence were used to select the final products for further testing: cumalative oxygen uptake via electrolytic respirometry, microbial growth, and compositional analysis of treated oil by GC and GC/MS. The commercial products were compared against oleophilic and inorganic fertilizers in a comprehensive protocol incorporating sterile and non-sterile controls. Respirometric vessels and shaker flask microcosms were set up for the comparative testing using weathered oil and natural seawater from Prince William Sound. The paper presents the protocol, the test results, and conclusions derived from the study.