A review of the use of natural products as starting points in the search for new pharmaceuticals, covering the broad areas of “Drugs affecting the centeral nervous system, ” “Neuromuscular blocking drugs,” “Anticancer drugs,” “Marine sources,” “Antibiotics,” “Cardiovascular drugs,” “Antiasthma drugs,” and “Antiparasitic drugs.” The review covers more than 100 years of development, from “old” drugs, such as morphine and quinine, to very recent discoveries, such as conotoxin and galantamine, and includes a discussion of the attributes of natural products as leads in the drug discovery process. Between 1990 and 2000, a total of 41 drugs derived from natural products were launched on the market by major pharmaceutical companies. In the chosen examples, the process of drug development is traced from the discovery of the activity of the natural compound, through chemical modification and biological evaluation, to either success or failure as a clinical product, highlighting the very different pathways to innovation that occur in each product.