The introduction of foreign genes constitutes a powerful tool with which to study and improve the genetic resources of plants, Transgene expression levels and expression patterns can be adjusted by combining the protein coding region with a suitable promoter. There is a diverse spectrum of endogenous plant promoters and these are currently being broadened by the development of chimeric promoters that respond to otherwise inactive chemicals. This range includes promoters that respond to inducers such as the antibiotic tetracycline, the steroid dexamethasone, the copper ion, ethanol or the agrochemical RH-5992, These chimeric promoters offer a range of options for transgene design for experimental and field use.