Measurement of the ability of mice to balance on a rotating rod or cone is often used as a measure of impaired motor function. In most of these procedures the mice must be trained prior to the test. In the new screen test described in this paper, untrained mice are used in a 60 sec test which measures the ability of mice to either climb to the top of or cling to the bottom of a horizontal screen. The ED50 values obtained for failure to reach the top of the horizontal screen are similar to those obtained with the rotarod; the values for falling from the screen are somewhat higher. With both of the horizontal screen measures there were fewer control failures than in the rotarod procedure.