Objective: To assess the effect of exercise training by using the Nintendo Wii Fit video game and balance board system on balance and gait in adults with Parkinson disease (PD). Design: A prospective interventional cohort study. Setting: An outpatient group exercise class. Participants: Ten subjects with PD, Hoehn and Yahr stages 2.5 or 3, with a mean age of 67.1 years; 4 men, 6 women. Interventions: The subjects participated in supervised group exercise sessions 3 times per week for 8 weeks by practicing 3 different Wii balance board games (marble tracking, skiing, and bubble rafting) adjusted for their individualized function level. The subjects trained for 10 minutes per game, a total of 30 minutes training per session. Main Outcome Measurements: Pre-and postexercise training, a physical therapist evaluated subjects' function by using the Berg Balance Scale, Dynamic Gait Index, and Sharpened Romberg with eyes open and closed. Postural sway was assessed at rest and with tracking tasks by using the Wii balance board. The subjects rated their confidence in balance by using the Activities-specific Balance Confidence scale and depression on the Geriatric Depression Scale. Results: Balance as measured by the Berg Balance Scale improved significantly, with an increase of 3.3 points (P=.016). The Dynamic Gait Index improved as well (mean increase, 2.8; P=.004), as did postural sway measured with the balance board (decreased variance in stance with eyes open by 31%; P=.049). Although the Sharpened Romberg with eyes closed increased by 6.85 points and with eyes opened by 3.3 points, improvements neared significance only for eyes closed (P=.07 versus P=.188). There were no significant changes on patient ratings for the Activities-specific Balance Confidence (mean decrease,-1%; P=.922) or the Geriatric Depression Scale (mean increase, 2.2; P=.188). Conclusions: An 8-week exercise training class by using the Wii Fit balance board improved selective measures of balance and gait in adults with PD. However, no significant changes were seen in mood or confidence regarding balance.