GeneChip (Affymetrix, Inc., USA) employs a specific method for spotting DNA probes on chips, which is different from any other DNA chips, and can complete the whole process from sample preparation to data construction and analysis. The GeneChip system can be applied to both gene expression analysis and genomic mutation analysis, which would play an important role in human genome analysis in the future. Techniques for data construction ("wet" experimental techniques), which are the major components in the GeneChip system, are generally established as routine work in the first screening process in most laboratories worldwide. The most important point would be how we exchange experimental data produced by researchers and gene/genome information available both on the public and the commercial bases so that we reduce useful information on gene expression. Recently, the center of the research has been shifting to computing technology for data processing ("bioinformatics"). This article separately deals with gene expression analysis and genomic analysis, with emphasis on bioinformatics. We describe the data on gene expression screening, the gene targeting process, the analysis of genomic DNA mutations using the P53 probe array, and the HuSNP mapping assays, by presenting our experimental examples.