Differences in body mass index trajectories and their association with cardiovascular disease mortality in men and women with coronary heart disease. To investigate differences in longitudinal change in body mass index (BMI) over a median follow-up of 6.3 years among patients with a diagnosis of coronary heart disease (CHD), and its relationship with CHD mortality. Longitudinal data for 4859 adults (age range 34-81 years) with newly diagnosed CHD from the Heart Protection Study was used. Over a median 6.3 years, 679 (13.7%) men and 982 (20.0%) women died. In both genders, most of the variation in BMI change was not explained by changes in smoking, physical activity, medications, alcohol use or psychological distress. After accounting for these variables, men and women had similar annual changes in BMI (0.09 and 0.08 kg/m(2)/year, respectively). However, BMI trajectories were different between genders and this difference in BMI change was significantly associated with the risk of death. Among men and women, higher BMI change was associated with increased risk of death in a log-linear fashion. The risk of death was 50% higher for men with a BMI change of 0.2 kg/m(2)/year compared with those with no change (risk ratio [RR] 1.50, 95% CI 1.21-1.85), and similarly, the risk of death was also 50% higher for women with a BMI change of 0.2 kg/m(2)/year compared with those with no change (RR 1.50, 95% CI 1.23-1.81). In people with a diagnosis of CHD, there are gender differences in BMI change over time, and this is related to a significantly higher risk of death. These findings provide support for a preventative approach for patients with CHD.