In laparoscopic surgeries, because of lack of tactile sensation and 3D visual feedback, it is difficult to identify the position of blood vessels intraoperatively. An accidental injury to a blood vessel could result in change of laparoscopic procedures to open surgery. A noninvasive, reliable, and economical method to detect blood vessels during laparoscopic and endoscopic procedures would be very useful. In this study we have examined the usefulness of narrow-band imaging. The contrasts and color differences between the blood vessels and the adjacent tissues were measured using narrow-band imaging and conventional broadband imaging. Wilcoxon signed-rank test was used as a statistical test for evaluating the differences between the two groups. By using narrow-band illumination of 530-550 nm, the contrast of the blood vessels was greatly improved. The performance of this technique is evaluated for detection of the artery and vein in the laparoscopic surgery on a pig. The results demons...