We have now isolated the great majority of genes encoding enzymes of storage oil biosynthesis in plants. In the past two years, particular progress has been made with acyltransferases, ketoacyl-acyl carrier protein synthetases and with desaturases and their relatives. In some cases, these enzymes have been reengineered to create novel products. Nevertheless, the single or multiple insertion of such transgenes into oil crops has not always led to the desired phenotype. We are only now beginning to appreciate some of the complexities of storage and membrane lipid formation, such as acyl group remodelling and the turnover of unusual fatty acids. This understanding will be vital for future attempts at the rational engineering of transgenic oil crops. In parallel with this, the domestication of plants already synthesising useful fatty acids should be considered as a real alternative to the transgenic approach to producing novel oil crops.