Jatropha curcas (L.) is a perennial plant of the spurge family (Euphorbiaceae). Recently, it has received much attention as a potential source of vegetable oil as a replacement for petroleum, and, in particular, the production of biodiesel. Despite the interest that is being shown in the large-scale cultivation of J. curcas, genetic resources remain poorly characterized and conserved and there has been very little plant breeding for improved traits. At present, the varieties being used to establish plantations in Africa and Asia are inedible. The meal obtained after the extraction of oil cannot, therefore, be used as a source of animal feed. Naturally existing edible varieties are, however, known to occur in Mexico. The toxic components of J. curcas seeds, the potential for plant breeding to generate improved varieties, and the suitability of J. curcas oil as a feedstock for biodiesel production are discussed.