db/db mice is one of most widely used animal models in studying the cellular and molecular mechanisms of metabolic disorders,such as diabetes,hyperlipidemia,and obesity.The mice carry spontaneous point mutations in the gene encoding the leptin receptor,leading to leptin receptor inactivation.Since homozygous db/db mice are sterile,the maintenance of db/db mice requires breeding between heterozygous pairs,which makes genotyping essential for the identification of offspring.The aim of this study was to develop a quick and highly repeatable method for genotyping db/db mice,which comprised only three simple steps:genomic DNA is extracted from either tail tips or ear notches via alkaline lysis (～20 min);samples are then subjected to tetra-primer amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) using specially designed and validated primer sets (～1.5 h);finally,genotypes are be determined by resolving PCR products on regular DNA electrophoresis (～10 min).The entire db/db mice genotyping procedure can be performed using regular Taq polymerase and PCR amplification within 2 h.Other advantages of this method include high sensitivity and reproducibility.Minimal amounts of tissue from mice are required,and genomic DNA samples can be stably stored at room temperature for up to one month.In conclusion,the method is simple,cost effective,sensitive and reliable,which will greatly facilitate studies using db/db mice.