Background Moderate physical activity is protective against coronary heart disease (CHD) and diabetes, both important public health problems among UK South Asian (Indian, Pakistani and Bangladeshi) ethnic groups. We assessed the evidence that physical activity is lower in South Asian groups than in the general population. Methods We carried out a systematic literature review of studies describing levels of physical activity and fitness in UK South Asians using MEDLINE, EMBASE, the Cochrane databases, hand searching of relevant journals and review of reference lists. Results We identified 12 studies in adults and five in children. Various methods were used to assess physical activity and fitness, but all the studies reported lower levels among South Asian groups. The differences were substantial, particularly among women and older people. For example, the Health Survey for England found that Indian, Pakistani and Bangladeshi men were 14, 30 and 45 per cent less likely than the general population to meet current guidelines for physical activity. Limited information was provided about translation and adaptation of questionnaires. Conclusion Levels of physical activity were lower in all South Asian groups than the general population and patterns of activity differed. No studies used validated measures. Insufficient attention has been paid to issues of cross‐cultural equivalence. With these caveats, low levels of physical activity among UK South Asian ethnic groups may contribute to their increased risk of diabetes and CHD. Closer attention to validity, translation and adaptation is necessary to monitor changes and assess the effectiveness of interventions to increase physical activity.