This review discusses fatty acid modification of oilseeds with additionai emphasis on production of oxygenated deriva?ives. In a relatively short periud, iess lhan a decade, our understanding of the enzymes involved in plant fatty acid syn thesis has increased to the point where we understand how they might be used in oilseed modification. Further, through modern molecular biological techniques, the actual genes for many of these important enzymes have been cloned. Use of genetic transformation systems has allowed us to fundamentally alter the normal biosynthetic pathways in highly specific ways, in manners that would be either difficult or impossible using traditional breeding techniques. A!teration of plant lipid biosynthesis is not restricted to using genes from the plants themselves, but interspecitis transfer is possible, either from completely unrelated plant species (often of no commercial va!ue but possessing unusual biochemical properties) or from animals, fungi, and prokaryotic organisms. In this way 'designer' piants possessing altered metabolism, tailored to the interests or needs of certain industries, nutritionists, and the consumer can be created.