OBJECTIVE: This paper aimed to investigate androgen, androgen receptor level and AR gene CAG length polymorphism associated with obesity in older males.METHODS: 323 males aged from 60-92 years old were randomly selected from Wanshoulu area,Beijing.Luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2) and total testosterone (TT) were measured by chemiluminescence technique.Free testosterone (FT), sex hormone binding globulin (SHBG) and dehydroepiandrosterone sulphate (DHEA-s) were measured by ELISA.Mean fluorescent channel (MFC) of androgen receptor in peripheral lymphocyte was analyzed by flow cytometry.DNA sequencing of the CAG repeat from the N-terminal domain of the first exon of the AR gene were analyzed by applied Biosystems 3730xl DNAAnalyzer.