The purpose of this article is to summarize the present knowledge on biotechnological research into isoflavonoid phyto-oestrogens. The physiological and pharmacological properties of isoflavones are discussed in the Introduction. The accumulation of phyto-oestrogens by plant cell and tissue cultures is reviewed. A special emphasis is put on the influence of basic experimental media and physiological factors on the production of isoflavonoids in in vitro cultures. The potential role of the transformation process as well as the techniques (including infection with bacteria and particle bombardment) and the various technological procedures (elicitation, feeding experiments) in isoflavone biosynthesis is discussed. Moreover, this chapter deals with the in vitro cultures of legume plants oriented for selective accumulation of phyto-oestrogens.