Book excerpt: Major skin diseases, including acne, psoriasis and eczcma, affect the majority of the population at some time in their lives. In general, these diseases are physically and psychologically disfiguring for the sufferers; furthermore, by their very chronic nature skin diseases, unlike most other disease processes, present both acute and chronic therapy problems. In addition, the chronic nature of these diseases can present certain economic problems. Firstly, chronic therapy is becoming increasingly expensive and secondly, patients adhering to a strict treatment regimen will frequently be absent from their gainful employment for either medical consultation or treatment. Given that in all NATO countries the average age of the population is continually increasing, these chronic skin diseases will increase in importance in the coming years. Furthermore, as the average population age increases, additional disease processes such as skin photodamage and carcinogenicity risk becoming major areas of therapeutic concern. This book reviews in detail the major scientific areas of interest for research and clinical scientists working in skin pharmacology and toxicology. The basic principles relating to an understanding of how drugs and chemicals may influence either the skin or the body as a whole are discussed in detail by recognized international scientific experts.