Purpose Smoking rates are known to be higher amongst those committed to prison than the general population. Those in prison suffer from high rates of comorbidities that are likely to increase their risk of cardiovascular disease (CVD), making it more difficult to manage. In 2016, a tobacco ban began to be implemented across prisons in England and Wales, UK. This study aims to measure the effect of the tobacco ban on predicted cardiovascular risk for those quitting smoking on admission to prison. Design/methodology/approach Using data from a prevalence study of CVD in prisons, the authors have assessed the effect of the tobacco ban on cardiovascular risk, using predicted age to CVD event, ten-year CVD risk and heart age, for those who previously smoked and gave up on admission to prison. Findings The results demonstrate measurable health gains across all age groups with the greatest gains found in those aged 50 years and older and who had been heavy smokers. Quitting smoking on admission to prison led to a reduced heart age of between two and seven years for all participants. Originality/value The data supports tobacco bans in prisons as a public health measure to reduce risk of CVD. Interventions are needed to encourage maintenance of smoking cessation on release from prison for the full health benefits to be realised.