It is not enough to select a chemistry, build a combinatorial library, and
test it for biologically active compounds. Chemical libraries can serve dif
ferent purposes and it is reasonable that they should be designed in Light
of their purpose and the information available on structural properties imp
ortant for biological activity. There is a rapidly expanding Literature on
the design of chemical libraries. This paper reviews that literature and co
mments on possible future directions of research on the design of chemical
libraries. (C) 1999 Elsevier Science B.V. All rights reserved.