The completion of the human genome project directly benefits the rapid development of DNA microarray technology.The application of microarrays in the study of human complex diseases is one of the pioneering fields in the post-genome era.This technology can be used to analyze genome-wide gene expression levels and profiles of virtually any type of cell and tissue,massive genotyping of single nucleotide polymorphism (SNPs) as well as gene sequencing.In addition,microarrays are also a very powerful tool for dissecting the genetic basis of complex diseases including obesity,a major public health concern in worldwide.Obesity is a complex disease determined by both genetic and environmental factors.The latest human obesity gene map has listed nearly 500 candidate genes and loci presumably associated or linked with obesity-related phenotypes.However,we have no knowledge in terms of how many genes are involved in the development of human obesity in a specific population,the nature of the variant alleles,or the mechanisms of how these variants alleles contribute to disease causation or predisposition.Using a creative combination of DNA microarray technology and traditional genetic methods,one can shed light on disease-causing genes in obesity and other complex disorders.