Fluorescence endoscopy is a new technique which allows a better endoscopic detection of nonvisible or difficult detectable malignant or premalignant lesions. Exogenously applied sensitizers accumulate selectively in malignant lesions and induce fluorescence after illumination with light of adequate wavelength. However, also endogenous fluorophores, different located in malignant or benign lesions, induce a different autofluorescence in these tissues. Meanwhile fluorescence endoscopy is a widely spread technique in urology using 5-aminolevulinic acid sensitization. In gastroenterology this technique seems promising in the detection of early cancers or dysplasia in patients with Barrett's esophagus or ulcerative colitis. This paper describes the current status and future development of fluorescence endoscopy in gastroenterology.