Background: Endometriosis is a disease causing severe pelvic pain. Previous data has shown that it has contributed to 15% infertility. Transvaginal Color Doppler is the noninvasive tool to assess ovarian endometrial vascularity. Aims and Objectives: To study severity of pain and compare it with site, size, laterality and vascularity of the lesions in terms of resistance index (RI), PI (Pulsatility index), PSV (Peak Systolic Velocity) and to compare the colour Doppler findings with ASRM Staging. Materials and Methods: Thirty women with endometriosis were studied in the Department of Obstetrics and Gynaecology. Pain intensity was assessed by visual analogue scale (VAS). A score of 1-3, 4-6 and ≥7 is classified as mild, moderate and severe pelvic pain respectively and were also classified based on the American Society for Reproductive Medicine staging. All the patients underwent trans-vaginal sonography and colour Doppler and the site, size, laterality and vascularity of the lesions in terms of RI, PI and PSV were assessed. Results: Mean RI, PI and PSV among the women with mild pain was 0.71±0.41, 1.49±0.29, 23.83±9.68, with moderate pain was 0.81±0.07, 2.01±0.40, 24.50±5.91 and with severe pain was 0.84±0.03, 2.33±0.14, 28.80±7.46 respectively. A significant correlation was obtained between RI and PI (p<0.001) with severity of pain whereas PSV had no relation with severity of pain (p=0.470).Mean RI and PI in stage I, II,III and IV were 0.71± 0.01 and 1.40± 0.10; 0.69± 0.02 and 1.54± 0.24; 0.80± 0.07 and 1.96± 0.51; 0.85± 0.03 and 2.24± 0.17 respectively. There was a positive correlation between RI and PI and advancing stages of endometriosis (p<0.001 and 0.001 respectively). The mean PSV in stage I, II, III and IV were 26.23± 10.42, 22.55± 4.38, 24.71± 9.38 and 26.82± 6.67 respectively. There was no correlation between PSV and severity of disease (p=0.736). Conclusion: RI and PI showed significant correlation with the severity of pain and advancing stages of endometriosis whereas PSV does not.