Light-induced fluorescence endoscopy (LIFE) has been shown to differentiate between normal mucosa and dysplastic lesions, and dysplastic lesions of the colon occult to routine white-light colonoscopy may thus be visualized by LIFE. We compared the sensitivity and specificity of LIFE to routine white-light colonoscopy in patients with colonic dysplasia. In a pilot study 20 patients with colonic adenoma, inflammatory bowel disease, or with a history of colon cancer were screened for colonic dysplasia during routine colonoscopy. Forty-two sites of mucosal abnormalities regarded as suspicious for dysplasia during white-light colonoscopy were additionally examined with a prototype LIFE system. Biopsies were taken from all 42 colonic sites. The LIFE images were classified as positive or negative for dysplasia. Sensitivity and specificity were calculated by correlating positive and negative findings to the histopathological results. Histopathology detected 21 adenomas with low-grade dysplasia and one with high-grade dysplasia. All dysplastic lesions were found by routine white-light endoscopy. The specificity of conventional white-light endoscopy was 80%. Of the 22 dysplastic lesions 20 were detected by LIFE (sensitivity 91%). The specificity of LIFE was 90% (two false-positive results). LIFE combined with conventional endoscopy may thus improve the detection of colonic dysplasia.