R. VERPOORTE Division of Pharmacognosy, section Metabolomics, IBL, Leiden University PO Box 9502, 2300RA Leiden, The Netherlands, Email: [email protected] In the past years the interest in plant secondary has increased rapidly. Three major reasons can be mentioned for this. First because plants are a major source for the production of medicines and the development of novel medicines; second because plants contain health promoting secondary metabolites, third because of the interest in the resistance of plants against pests and diseases in which the secondary metabolism plays a crucial role. Seven years ago we edited a book (Verpoorte and Alfermann 2000) on the engineering of plant secondary metabolism. A general overview was given of plant secondary metabolism, and the strategies one could envisage for engineering plant secondary metabolite pathways. Furthermore, a number of examples were presented describing the state-of-the-art of engineering plant secondary metabolism. Now we have again compiled a series of papers on the engineering of plant metabolism.