Objective: To evaluate the effects of laparoscopic ovarian drilling (LOD) on threedimensional (3D) power Doppler indices of ovarian stromal blood flow and serum vascular endothelial growth factor (VEGF) levels in women with polycystic ovary syndrome (PCOS).Design: Prospective controlled study. Setting: Minia University Hospital, Minia, Egypt. Material and methods: 30 clomiphene citrate resistant women with PCOS undergoing LOD and 30 fertile women with normal ovaries were recruited in this study. Hormonal profile, Doppler indices of ovarian stromal blood flow and serum VEGF assays before and after LOD were evaluated and compared between the two groups. Evaluation was done at the beginning of the study, 1 week after LOD and at 3 and 6 month follow up periods.Main outcome measures: 3-D power Doppler indices of both ovaries and serum VEGF concentration.Results: Before LOD, serum levels of VEGF, total testosterone (T), free androgen index (FAI), LH, LH:FSH ratio, total antral follicle count (AFC), total ovarian volume (OV) and the 3D power Doppler blood flow indices were significantly higher in the PCOS group than in the control group. After LOD, there was a significant reduction in the serum levels of VEGF, T, sex-hormone binding