Potentially transplantable kidneys experience warm ischemia, and this injury is difficult to quantify. We investigate optical spectroscopic methods for evaluating, in real time, warm ischemic kidney injury and reperfusion. Vascular pedicles of rat kidneys are clamped unilaterally for 18 or , followed by 18 or of reperfusion, respectively. Contralateral, uninjured kidneys serve as controls. Autofluorescence and cross-polarized light scattering images are acquired every using laser excitation (autofluorescence) and linearly polarized illumination (light scattering). We analyze changes of injured-to-normal kidney autofluorescence intensity ratios during ischemia and reperfusion phases. The effect of excitation with is also explored. Average injured-to-normal intensity ratios under excitation decrease from 1.0 to 0.78 at of ischemia, with a return to baseline during of reperfusion. However, during of warm ischemia, average intensity ratios level off at 0.65 after , with no significant change during of reperfusion. excitation results in no autofluorescence changes with ischemia. Cross-polarized light scattering images at suggest that changes in hemoglobin absorption are not related to observed temporal behavior of the autofluorescence signal. Real-time detection of kidney tissue changes associated with warm ischemia and reperfusion using laser spectroscopy is feasible. Normalizing autofluorescence changes under using the autofluorescence measured under excitation may eliminate the need for a control kidney.