Endometriosis was induced by autotransplantation of uterine tissue into the peritoneal cavity. Twenty-four rats, which had visually confirmed endometriotic implants on subsequent laparotomy, were randomized into three groups to receive imatinib (25 mg/kg/day, p.o.), anastrozole (0.004 mg/day, p.o.), or normal saline (0.1 mL, i.p.) for 14 days. After removal of endometriotic tissue and H & E staining, endometriosis score was determined according to a semiquantitative histological classification. Also, immunostaining with primary antibodies including VEGF, CD117, and Bax were used for immunohistochemical (IHC) examination.