Optical coherence tomography (OCT) is an emerging medical imaging technology that enables high-resolution, noninvasive, cross-sectional imaging of microstructure in biological tissues in situ and in real time. When combined with small-diameter catheters or needle probes, OCT offers a practical tool for the minimally invasive imaging of living tissue morphology. We evaluate the ability of OCT to image normal kidneys and discriminate pathological changes in kidney structure. Both control and experimental preserved rat kidneys were examined ex vivo by using a high-resolution OCT imaging system equipped with a laser light source at 1.3-microm wavelength. This system has a resolution of 3.3 microm (depth) by 6 microm (transverse). OCT imaging produced cross-sectional and en face images that revealed the sizes and shapes of the uriniferous tubules and renal corpuscles. OCT data revealed significant changes in the uriniferous tubules of kidneys preserved following an ischemic or toxic (i.e., mercuric chloride) insult. OCT data was also rendered to produce informative three-dimensional (3-D) images of uriniferous tubules and renal corpuscles. The foregoing observations suggest that OCT can be a useful non-excisional, real-time modality for imaging pathological changes in donor kidney morphology prior to transplantation.