Introduction: There is currently no efficient and reliable means of assessing the degree of ischemic damage in a potential donor kidney for transplantation. Photonic analysis of tissue is quick, noninvasive and portable. We hypothesized that ischemic damage to kidneys can be assessed by two novel photonic methods utilizing laser autofluorescence and polarized light scattering spectroscopy. Methods: Warm ischemia was induced in 35Lewis rat kidneys by clamping the renal pedicle for 5, 10, 20, 30, 60, 90 and 120 minutes (5 rats at each time point). Next, ischemic and control (non-injured) kidneys from each rat were flushed with Euro-Collins solution and stored on ice at 4°C. A laser wavelength of 335 nm was used to excite tissue on the surface of each kidney at 4°C, and autofluorescence images at different spectral bands as well as emission spectra from various points in every kidney were measured. In addition, cross-polarized light scattering images at 700 nm and 800 nm were recorded. The degree of tissue change was assessed by calculating the ratio of the average signal intensity of the injured kidney to that in the control kidney of the same animal. Results: The figure shows autofluorescence (dots) and light-scattering at 800 nm (triangles) intensity ratios for the studied ischemic injury times (± standard error bars). Correlation factors of auto-fluorescence and light scatte-ring with ischemic time were -0.65 and -0.84 (p < 0.0001, z-test), respectively.Conclusions: Optical spectroscopic characteristics of ischemic tissue correlate with ischemia time. Further study is necessary to correlate spectroscopic findings with postreperfusion graft function and to validate the method in a preclinical setting.