Since endometriosis is a proliferative disease we evaluated the presence of anti-apoptotic factor (Bcl-2) and pro-apoptotic factor (Bax) in deep pelvic endometriosis. A Cross-sectional observational study was performed at Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil. Forty women aged 26 to 46 years with deep endometriosis were selected. They had not been clinically treated for at least 3 months prior to surgery and then underwent surgical laparoscopy to treat the disease. During the surgery, tissue was collected from the uterosacral ligaments and the rectosigmoid; an endometrial biopsy was also performed as a control. All interventions were performed by the same surgeon. The specimens were sent for pathological and immunohistochemical analyses; endometriosis was confirmed in all patients. After the immunohistochemical reaction a semi-quantitative evaluation of the staining intensity (relative optical density-ROD) was conducted, applying the digital densitometric analysis system. In the uterosacral ligaments 97.5% of the specimens were positive for Bcl2 whereas in the rectosigmoid 100% were positive. In the endometrium we observed that 87.5% were positive for Bcl2. BAX expression was null in the rectosigmoid and in the endometrium. In the uterosacral ligaments 2.5% of the specimens expressed BAX. The relative optical density of Bcl2 was higher in the rectosigmoid and in the uterosacral ligament when compared to the endometrium, 0.141±0.002; 0.129±0.001, respectively (p<0.01). We concluded that the anti-apoptotic factor Bcl-2 was expressed in all studied specimens, but in a higher staining intensity in the rectosigmoid and in the uterossacral ligaments in comparison to the endometrium. The pro-apoptotic factor Bax had virtually no expression in the studied tissues.