Traditional plant breeding techniques have had a major impact on the Australian cotton industry through the production of the widely successful CSIRO varieties Siokra and Sicala. This science will continue to provide the Industry with the most relevant varieties for Australia's unique environmental conditions, but now it will be enhanced by the new technology of genetic engineering. Breeders in the past have been very restricted in the genetic resources that they can call upon for variety improvement and have only been able to produce new re assortments of genes already present in existing cotton varieties, or at most their very close wild relatives. Potentially useful genetic resources present in other plants or even non-plants have been inaccessible because of the sexual barriers to crossing between unrelated species. This genetic resource has now become accessible because of recent advances in recombinant DNA technology, the science of studying and manipulating genetic material. It is now possible to produce transgenic organisms, organisms containing genetic material from novel sources. The technology has been used in a variety of organisms from simple bacteria, yeasts and fungi, up to more complex organisms such as plants and even animals. The techniques have recently been extended to cultivated cotton, opening up tremendous possibilities for the improvement of our existing Australian cotton varieties.