Objective To determine the roles of retionoic acid receptor β(RARβ) gene methylation in the occurrence and development of breast cancer. Methods We screened the primary human breast tumors and normal breast tissues for RARβ gene promoter methylation by methylation specify PCR(MSP), and the results were analyzed together with corresponding clinical pathological data. Results The frequency of RARβ gene methylation in 192 cases was 26%(50/192), however no RARβ gene methylation was found in normal breast tissue...