Soybean (Glycine max Meff.) oil is primarily composed of five fatty acids; palmitic acid (similar to 13%), stearic acid (similar to 4%), oleic acid (similar to 18%), linoleic acid (similar to 55%) and linolenic acid (similar to 10%). The average U.S. production of soybean oil from 1993 to 1995 was 6.8 billion kg and in 2002 soybeans were harvested from more than 30 million ha across the U.S., which accounts for 40% of the total world soybean output. This production capacity accounts for more than 50% of the total available biobased oil for industrial applications. A useful industrial application of soybean oil is in biodiesel blends. On a liquid basis, the total soybean oil production capacity would be equivalent to 1.9 billion gal of diesel, about 6.9% of the diesel fuel consumed in the United States for transportation in 1996. A number of positive attributes are realized with the use of soybean oil-derived biodiesel, including enhanced biodegradation, increased flashpoint, reduced toxicity, lower emissions and increased lubricity. However, the two parameters that have limited usefulness of a soybean oil-derived biodiesel as a fuel are oxidative instability and cold flow in northern climates. The latter is not an issue in warmer environments, and thus soybean oil modifications designed to maximize engine performance should be targeted with marketplace locale considerations in mind. Implementing the tools of biotechnology to modify the fatty acid profile of soybean for locale performance enhancement may increase the attractiveness of biodiesel derived from this commodity crop. (c) 2004 Elsevier B.V. All rights reserved.