This systematic review evaluates interventions using active video games (AVGs) to increase physical activity and summarizes laboratory studies quantifying intensity of AVG play among children and adults. Databases (Cochrane Library, PsychInfo, PubMed, SPORTDiscus, Web of Science) and forward citation and reference list searches were used to identify peer-reviewed journal articles in English through March 2011. Studies that used off-the-shelf AVGs to increase physical activity with quantitative outcomes or studies that quantified intensity of AVG play were included. Information on sample characteristics, AVGs employed, study design and conditions, outcome measures, results, and conclusions was extracted by two researchers. Intervention studies were ranked on design quality. Thirteen interventions and 28 laboratory studies were identified. All laboratory studies demonstrated that AVGs are capable of providing light-to-moderate intensity physical activity. However, only three interventions supported AVGs as an effective tool to significantly increase physical activity or exercise attendance. As AVGs are becoming more popular, additional research is needed to determine how to capitalize on the potential of AVGs to increase physical activity. (Contains 6 tables and 1 note.)