A new implantable window was developed in order to study the native microcirculation of the rabbit ear. The responses of the ear microvasculature to total body cooling were studied before and after implantation of the window. No differences were found between arteriolar and venular vasoconstriction with cooling before and after implantation of the window. Arteriolar constriction was significantly greater than the venular response both before and after placement of the window (P = 0.014). Surface skin temperature of the instrumented and control ears was similar at room temperature (35.2 +/- 2.6 versus 36.1 +/- 1.0 degrees, respectively; P = 0.280); however, the instrumented ear was slightly warmer during cooling (17.9 +/- 1.9 versus 15.2 +/- 3.1 degrees; P = 0.024), suggesting increased blood flow in the instrumented ear. Details of construction and implantation of the window are described.