Abstract: Objective:To investigate the correlation between the expression of angiogenic factors (MVD, IGF-1, and STAT 3) in colorectal carcinoma and adenoma and the microvascular characteristics under narrow band imaging (NBI), in order to evaluate the fea -sibility of NBI in real- time observation of angiogenesis. Methods:Patients with pathologically confirmed colorectal polyps were re-cruited and examined by NBI. Vascular patterns were classified into typeⅠ(invisible or faintly visible), type Ⅱ(clearly visible and regularly arranged in a round, oval honeycomb-like pattern), and type Ⅲ(clearly visible and irregularly arranged in terms of size and caliber or irregularly winded). Immunohistochemical staining was performed to determine the expression of CD34, IGF- 1, and STAT 3. Histological results were compared with the vascular patterns under NBI. Results:The NBI endoscopy results of64sites (15adenocar -cinomas, 29adenomas, and 20normal tissues) from 58patients were introduced and examined in this study. Adenomas ranked the first (82.1%,23/28) among the vascular pattern Ⅱcases, whereas early adenocarcinomas dominated the vascular pattern Ⅲcases ( 66.7%, 10/15). The expression levels of MVD-CD34and IGF- 1 in normal mucosa, adenomas, and adenocarcinomas were significantly differ-ent ( P<0.0001and P=0.0062, respectively). All the expression levels of MVD-CD 34, IGF- 1, and STAT 3 in sites displaying vascular pat -terns Ⅰ, Ⅱ, and Ⅲwere significantly different (P<0.0001, P=0.0010, and P=0.0055, respectively). Spearman correlation coefficients between the NBI vascular patterns and the MVD-CD 34, IGF- 1, and STAT 3 expression levels were 0.67, 0.41, and 0.40, respectively. Conclusion:Vascular pattern analysis through an NBI system can be a promising tool to evaluate angiogenesis of colorectal lesions in real-time endoscopic observation.