It has been long recognized that local tissue temperature may osculate due to vascular thermo-regulation under hyperthermic conditions. To effectively heat the target tissue while sparing its surroundings, it is necessary to understand and then to control the temperature oscillation. A model based on the pig kidney vasculature was developed to study the transient temperature variations in the kidney when subjected to heating in a thermal bath. In the medullary region, a vascular model previously developed in (Chen and Xu, 2000) was used to account for the conjugate heat transfer between the paired artery and vein, and their surrounding tissue. Considering that numerous small vessels exist in the cortex region, the Pennes bio-heat transfer equation was used for modeling in this region. A code was written to numerically compute the 3-D transient temperature distribution in the kidney subjected to heating. To examine the validity of the model, experiments were performed to measure the temperatures and perfusion rates using thermistor microprobes in the cortex of the preserved pig kidney. This model will be utilized for future studies to investigate the relationships among the local blood perfusion rate, the heating rate, and the tissue temperature oscillation.