Over the years 1981 to 2001 there has been a rapid evolution of research into medicinal plants. The major improvement has been the introduction of simple and predictive bioassays for bioactivity-guided isolation. Radical developments in separation methods have also taken place. Another important addition has been the development of hyphenated techniques involving HPLC: LCrUV, LC/MS, LC/Msn and LCfNMR. These are indispensable nowadays for the early detection and identification of new compounds in crude plant extracts. Hyphenated techniques allow an efficient targeted isolation approach for the discovery of new lead compounds. Other areas of increasing importance include the investigation of toxic constituents of plants and phytomedicines, and the effects of genetic modifications on plant secondary metabolites.