Polarization Sensitive Optical Coherence Tomography (PS- OCT) was used to image the reduction of birefringence in biological tissue due to thermal damage. Through simultaneous detection of the amplitude of signal fringes in orthogonal polarization states formed by interference of light backscattered from turbid media and a mirror in the reference arm of a Michelson interferometer, changes in the polarization due to the optical phase delay between light propagating along the fast and slow axes of birefringent media were measured. Inasmuch as fibrous structures in many biological tissues in uence the polarization state of light backscattered, PS-OCT is a potentially useful technique to image the structural properties of turbid biological materials. Birefringence of collagen, a constituent of many biological tissues, is reduced by denaturation that takes place at a temperature between 56-65 0 C, thus providing an "optical marker" for thermal damage. Images showing reduction of birefringence due to thermal damage in porcine tendon and skin are presented and demonstrate the potential of PS-OCT for burn depth assessment.