Automatic stepping is an involuntary disorder with cyclic alternating leg movements which causes patients to appear as if walking. We report automatic stepping in patients with progressive basilar artery territory infarcts. These movements consisted of spontaneous knee flexions and ankle dorsiflexions with intermittent hip flexions, and alternating leg movements without provocation. Intervals between the movements were various from 3 to 30 seconds. Serial diffusion- weighted MRI revealed that progressive lesions were mainly located in the pontine tegmental areas.