New technology for analyzing complex genomes is an important area of modern molecular biosciences. This book focuses on a recently developed genome scanning method, termed two-dimensional 2-D DNA typing, which is based on a combination of two independent electrophoretic separation principles. When separation according to size is coupled to separation according to base-pair composition, complex genomes can be resolved in a number of DNA fragments. These fragments or subsets can be visualized, for example, by hybridization analysis with specific probes. Genome scanning by 2-D DNA typing finds applications in many areas, such as linkage and association studies for identifying genetic traits in humans, animals and plants, studies on genetic instabilities in cancers, classification studies in bacteria and other lower organisms, studies on human mutation rates, and the identification of mutations in large genes.