Purpose: To study the anti-endometriotic effect of Angelica sinensis (Oliv.) Diels extract (ASDE) in human endometriotic cells and rats.Method: Forty female rats were randomly divided into four groups (10 rats/group): control, endometriosis+danazol, endometriosis+high dose of ASDE and low dose of ASDE. The rats were orally administered either vehicle (200 μL of PBS) alone or ASDE (140, 280 and 560 mg/kg/day) for 5 weeks. Danazol was used as the control drug. After induction of endometriosis for 4 weeks, the rats were sacrificed by cervical dislocation and the peritoneum and visceral organs examined visually to measure the number of endometriotic lesions. Serum levels of cancer antigen 125 (CA-125) and interleukin 13 (IL-13), interleukin 18 (IL-18) and tumor necrosis factor-alpha (TNF-α) of peritoneal fluids of rats were measured using ELISA kits. Western blot assay was performed to measure the levels of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9)  expressions after 24 h of treatment with ASDE (30, 60, and 120 μg/mL).Results: ASDE-treated rats displayed reduced numbers of total endometriotic lesions when compared with vehicle-treated controls (p < 0.01). When the rats were treated with high dose of ASDE, serum CA-125 level, as well as IL-18 and TNF-α levels in peritoneal fluids were significantly lower than that of the control group (p < 0.01); however, IL-13 level in peritoneal fluids was significantly higher than that of the control group (p < 0.01). ASDE treatment significantly suppressed the levels of MMP-2 and MMP-9 protein in 11Z cell (p < 0.01).Conclusion: The results reveal that ASDE exhibits significant anti-endometriotic effect by inhibiting inflammatory factors in rats. Thus, the plant extract can potentially be developed for the clinical management of endometriosis. Keywords: Angelica sinensis, Endometriosis, Cancer antigen, Endometriotic lesions, Matrix metalloproteinase