Organisms frequently synthesize enzymes in multiple molecular forms to catalyze the same basic biochemical reactions. Each of these enzymes exhibit somewhat different kinetic properties and perhaps, are also located in a specific part of the metabolic structure of the cell. This isozymic multiplicity only emphasizes the biochemical versatility and refinement of the genetic-enzyme structure of organisms.Since the isozyme concept was formulated some thirty-five years ago, and especially after the advent of transgenic technology, the deep interest in the area has led to thousands of research investigations and many international conferences on the subject. This volume is a collection of selected oral presentations from one such conference, which is by now well-known.Topics includes: isozymes in population and evolution genetics, isozyme markers in gene mapping, isozymes in plant genetics, role of isozymes for normal physiology, the use of isozymes in human population biology, molecular organization and developmental regulation of isozymes and other related topics.