There are five main subject areas in this volume in the series on medicinal chemistry. The first is a review of the understanding of Alzheimer's disease and the development of drugs for its treatment; the second, looking at recent efforts in modifying a naturally occuring anticancer (campothecin) for chemotherapy; the third covers the problem of getting a drug to a specific site within the context of phosphates and phosphonates; a survey of sterilization using aldehydes for the destruction of microbes both inside and outside the human body is reviewed in the fourth; and the last chapter is an account of the progress made in the biologically active enantiomer for complex synthetic asymmetric drug molecules.