Optical coherence domain reflectometry is applied here to the study of diffusive biological tissue. This non-contact technique allows us to probe the light reflected at a tissue interface, and the back scattered light through the tissue thickness, with very fine spatial resolution and large dynamics. We present such measurements performed on an arterial wall, with a spatial resolution of 15 μm and a dynamic of 110 dB, and deduce from these measurements an attenuation coefficient Σt = 19 cm-1 through the arterial wall.