Natural products and their derivatives are well established in clinical res
earch and for medical applications. There are excellent drugs available fro
m various plants and microorganisms. Recent developments in the different s
creening techniques have accelerated the discovery of new compounds. Furthe
rmore,the investigation of compounds of marine origin, which have been more
difficult to obtain, has become possible. With the help of combinatorial m
ethods, natural products can be modified to optimize their use for medical
applications. Due to the enormous medical potential, modern research on nat
ural products will also be important in the next century.