also chaos theory reached its zenith of popularity. Unfortunately, the popularity appears to have decreased in recent years, but their scientific relevance has not, of course. The article gives a survey on how chemical waves, which are, for example, produced in a Belousov-Zhabotinsky reaction, can be modelled. Sârbu and Pop add a fifth review on fuzzy soft-computing methods, which covers algorithms such as neural nets, genetic algorithms, and, particularly, fuzzy logic. These are of particular value for data analysis or pattern recognition if not suffciently enough data are available to phrase and/or answer a question and if a high precision of the calculated answer is not needed. The final treatise by Ekins and Swaan concludes the volume with an up-to-date review of enzyme modelling in terms of descriptors used within quantitative structureactivity relationship techniques with respect to drug absorption, metabolism, distribution, excretion and toxicology. The number of enzymes discussed in this last review is impressive.To summarize, also the present volume of the Reviews in Computational Chemistry contributes to the success story of this series. Needless to say that the 20th volume continues to provide detailed reference and author indices and a homogeneous layout throughout. The editors have done an excellent job and the book is a must on every book shelf of computational chemistry literature.