The mouse is an ideal model organism for studies of human disease, because mouse is physiologically very similar to human. Also, there is a large genetic reservoir of potential models of human diseases that has been generated. In addition, high-resolution genetic and physical linkage maps are now available and the sequence of mouse genome will be completed in the near future. Furthermore, the techniques necessary for the modification of mouse genome, such as transgenic and knockout techniques, and chromosome engineering methods have been established. These techniques enable us to introduce any mutations anywhere in the mouse genome. The methods for analyzing complex genetic diseases also have been developed. These advances facilitate the identification and cloning of mouse disease loci and the establishment of new models. It makes mouse the model organism of choice by academic and industrial researchers to study human diseases. In Part I of this review, we summarize the classical and modern approaches that provide the basis of establishing mouse model of human diseases. In the following parts, we will list more than 100 mouse models of human diseases. In most of these models, the mouse mutant phenotype closely resembles the human disease phenotype. These mouse models are valuable sources for the understanding of the human diseases and they can be used to develop strategies for prevention and treatment of the diseases.