Recently technological advances in optical imaging have shown the promise to provide high-resolution imaging of biotissues. Optical coherence tomography (OCT) enables cross-sectional imaging of highly scattering biological tissues at the axial resolution of 10 micrometers or less and at the depths of up to 2-3 mm, highly desirable for screening various kinds of superficial lesions and the invasion of these lesions. In this study, we applied OCT to examine normal and diseased bladder epithelium, and correlated the results with histological findings. OCT images of rat bladder demonstrate the potential of this method to clearly delineating the micro morphological structures of human bladder tissue. Our results show that the micro morphology of rat bladder such as the urothelium, submucosa and muscles is identified by OCT and well correlate with the histological evaluations. OCT detected edema, inflammatory infiltrates, and submucosal blood congestion, as well as abnormal growth of urothelium. By contrast, surface imaging, which resembles cystoscopy, provided far less sensitivity and resolution than OCT. The results suggest the potential of OCT for noninvasive diagnosis of both bladder inflammatory lesions and early urothelial abnormalities, which conventional cystoscopy often misses, by imaging characterization of the increases in urothelial thickening and backscattering.