Cancer cervix accounts for 6.29% of cancer in women in India. Aim of this study is to prove the diagnostic efficacy of the colposcopy by correlation between Reid’s Colposcopic index and histopathological report of CIN. This non-randomized study done for one year in IOG and 180 –KGH by convenience sampling. All women with VIA/VILI positive were subjected to colposcopy. The margins of atypical cervical epithelium are graded and assessed with iodine staining Reid’s scoring based on all findings was made. Colposcopy detailed biopsy was taken. The sensitivity, specificity and predictive values were calculated with diseases threshold of CIN 1 as well as CIN 2. About 166 women had participated. 83 women (51.8%) belonged to 41-60 years. 58.1%women had 2 living children. premenopausal (87) and postmenopausal (73) were almost equal. 56 women had postmenopausal bleeding, 45 had HMB and 87 women had white discharge. RCI findings were 45(28.1%) benign, 53(33.1%) had CIN, 39 (25.4%) had CIN 2 and 23(14.4%) had CIN 3 the biopsy findings were 49(34.4%) benign, 55(34.4%) had CIN 1 29(18.1%) had CIN 2 17(16.2%) women invasive carcinoma the level of agreement between colposcopy RCI and biopsy findings using kappa statistics was 72% (P-0.045). spearman correlation was 0.85 (P<0.001) ROC showed 91.9% sensitivity 73.5%specificity, 80% PPV and 88%NPV. There is high sensitive and specificity with 72% agreement of biopsy finding, colposcopy RCI has good correlation with determination of CIN. Hence it is a reproducible technique which is easy to implement in colposcopy clinics.