Two subjects with Parkinson disease (PD) who had difficulty turning, and freezing of gait triggered by turning, participated. Subjects completed four blocks of turning trials. Three blocks were conducted in the absence of treadmill intervention. Both subjects had consistent freezing across blocks prior to training and evidenced more freezing when turning left than right. The final block of turns was performed after 10-15 min of training leftward turning on a rotating circular treadmill. Following training: (1) neither subject froze during leftward turns, (2) muscle activity normalized, and (3) turning times decreased for leftward turns.