Czechoslovak Society for Microbiology and Institute of Microbiology of the Czechoslovak Academy of Sciences organized an international symposium "Extracellular enzymes of microorganisms" in September 1986. The symposium took place in a small South-Bohemian town Bechyne and this book includes the main contributions presented at the meeting. The study of microbial extracellular enzymes is a rapidly developing field of science, which is important both from practical and theoretical point of view. On one hand, microbial enzymes are nowadays broadly used in various branches of industry, medicine and agriculture, on the other hand, their study contributes substantially to our knowledge of problems of protein secretion, regulation of protein synthesis as related with growth and cytodifferentiation and - las,t but not least - it brings data important for the elucidation of evolutionary pathways. Microbial enzymology also represents a bordering area between different scientific disciplines such as microbiology, biochemistry, genetics, biotechnology and other and demonstrates that only their integration brings about a substantial progress in the development of our understanding of biological processes. The symposium in Bechyne was a small one but the contributions of scientists from 15 different countries have brought information on recent approaches and developments in this field. I hope that this meeting was useful in facilitating closer contacts between specialists from different scientific areas and also contributed to a better understanding among people from different parts of the world.