Women with polycystic ovary syndrome (PCOS) demonstrate a high prevalence of obesity across all populations studied. The role of decreased energy expenditure through reduced physical activity in contributing to obesity in PCOS is not well studied. The independent benefits of exercise in improving metabolic disease, cardiovascular health, and diabetes have been shown in the general population. Moderate activity incorporated into daily activities appears to be as effective in the reduction in diabetes risk and cardiovascular disease as that achieved with vigorous activity and may be more sustainable over the long-term. The role of physical activity in the management of the reproductive dysfunction of PCOS is less established, although lifestyle change incorporating increased physical activity with reduced caloric intake has shown benefit in small published trials. Studies of weight loss demonstrate an essential role for increased physical activity in maintenance of weight loss over the long-term although minimal effect in the achievement of weight loss with exercise alone. Further studies of the role for exercise in the management of reproductive dysfunction in PCOS as well as clarification of the type, frequency, and duration of exercise to achieve the best outcomes are needed.