Rapid socioeconomic development in the countries of the Gulf Cooperation Council (GCC) has resulted in demographic and epidemiological transitions, with obesity, diabetes and other chronic diseases becoming the leading causes of morbidity and mortality. This emerging disease pattern is often attributed to physically inactive lifestyles. Given that there is no consolidated evidence on physical activity participation, we reviewed studies to examine prevalence and gender differences among GCC adults. PubMed, CINAHL and reference list searches identified eight relevant studies. Based on the best-available data, the prevalence of adults being physically active for at least 150 min week−1 (based on the international standard definition) ranged from 39.0% to 42.1% for men and 26.3% to 28.4% for women. Men were significantly more active than were women. Prevalence estimates for participation in physical activity in the GCC States are considerably lower than those for many developed countries. Studies using standardized methodologies with nationally representative samples are urgently required. Identifying prevalence and gender variations provides the basis for understanding the unique socio-cultural and environmental factors contributing to physical inactivity among adults in the countries of the GCC. This understanding must then inform population-health strategies to address the rising prevalence of obesity, type 2 diabetes and other chronic diseases.