Objective The aim of this study was to investigate the contribution of physical inactivity to the excess mortality from coronary heart disease (CHD) observed in the UK South Asian population.

Design An observational longitudinal study with follow-up mortality data from NHS registries.

Setting Data from the Health Survey for England, 1999 and 2004.

Participants 13 293 White and 2120 South Asian participants aged ≥35 years consented to the mortality follow-up.

Main outcome measures Deaths from CHD.

Results South Asian participants were more likely to be physically inactive than white participants (47.0% vs 28.1%). Deaths from CHD were more common in UK South Asian participants, particularly among Pakistani and Bangladeshi groups (HR 2.87, 95% CI 1.74 to 4.73), than in UK white participants, and South Asian people experienced an event at an age on average 10 years younger than white people. Physical inactivity explained >20% of the excess CHD mortality in the South Asian sample, even after adjustment for potential confounding variables (including socioeconomic position, smoking, diabetes and existing cardiovascular disease).

Conclusions Physical inactivity makes a significant contribution to the excess CHD mortality observed in the South Asian population in the UK. This highlights the importance of prioritising the promotion of physical activity in this high-risk population.