Aim: To define the prognostic significance of menstrual timing of breast cancer (BRCA) surgery, its interaction with estrogen receptor (ER) and angiogenesis. 
Methods: Prospective randomized involving 40 premenopausal BRCA patents with accurate triangulation of surgery 
(no multistage) in objectively defined menstrual cycle side (transvaginal ultrasound-serum progesterone), 
immunocytochemical stain for estrogen receptors and factor VIII, 5 years follow up with well proved finite end points.{ 
disease free survival (DFS)and disease free time (DFT)}. 
Results: Resected Tumors in the follicular phase had more angiogenic score (P, 0.001) plus higher micro vessel count 
(P, 0.001). Patients who underwent surgery in the luteal phase had better (DFS) (P, 0.02). On univariant analysis the 
menstrual timing (P, 0.01) and angiogenic score (P, 0.01) predicted the DFS, their bivariant analysis found luteal phase subset with low angiogenic score had the best prognosis (P, 0.04), but on multivariate analysis the menstrual timing was the discriminant factor (P, 0.04), the predictors for DFT were menstrual timing (P, 0.02), and ER status (P, 0.04) with insignificant difference on subset analysis. 
Conclusion: Menstrual timing represented grade II prognostic factor, with better DFS, DFT for patients operated in the luteal phase. It acts through angiogenesis modulation.