Objective To assess the clinical effect ofEleng Capsulein the treatment of endometriosis of qi-stagnation and blood-stasis syndrome, and explore its mechanisms. Methods Seventy-five patients with endometriosis were recruited and divided randomly into three groups,eleng group, nemestran group and blank control group, 25 patients in each group. The changes of symptoms and signs were recorded before and after treatment;the serum levels of EMAb, CA125 and PRL were also examined. Results Compared with blank control group, the scores of dysmenorrhea were significantly reduced after treatment(P 0.05), and the size of ovarian endometria1 cysts obviously decreased(P 0.05), and the high serum levels of PRL, CA125 and EMAb were significantly reduced in both eleng group and nemestran group(P 0.05). But there was not any significant difference between eleng group and nemestran group(P 0.05). ConclusionEleng Capsulesignificantly relieves the symptoms and signs of endometriosis of qi-stagnation and blood-stasis syndrome possibly by down-regulating serum levels of PRL,CA125 and EMAb.