OBJECTIVE:To evaluate the curative effect of external application of the Chinese drug,Sanjierupi Gao,on mastalgia caused by mammary gland hyperplasia.METHODS:This randomized,double-blinded,and placebo controlled study enrolled 260 patients with mammary gland hyperplasia from five hospitals.Patients were randomly and equally divided in-to a Sanjierupi Gao treatment group and a placebo control group.An adhesive plaster was applied to the most painful area on either breast for 7 h a day.Treatment lasted for two menstrual cycles without application during menstruation.Mastalgia was used as the main index of curative effect.The change before and after treatment in days of mastalgia,the time to alleviate pain,pain extent,and severe pain scores were observed.RESULTS:Compared to the control group,the treatment group had significantly fewer days of mastalgia(P