Background and study aims We report a case series of 5 patients with collagenous colitis (CC) presenting with chronic watery diarrhea, who were subjected to magnifying, chromoendoscopy and narrow band imaging (NBI). Magnifying chromoendoscopy revealed whitish-clouded, honeycomb-like appearance at orifices of the crypts. NBI with high magnification revealed irregular caliber variation of the subepithelial capillary network. Presence of these features corresponded with histological characteristics of CC indicated by thickening of the subepithelial collagen layer. We concluded that magnifying image-enhanced endoscopy is a reliable tool to diagnose CC.