PURPOSE: Differences in cardiovascular risk factor levels have been suggested to contribute to the age-related excess risk of coronary heart disease (CHD). The aim of this study was to reliably quantify these contributions using a large prospective dataset. METHODS: We carried out an individual participant data meta-analysis of 41 cohort studies (n = 582,134) from Asia, and Australia and New Zealand. Cox models were used to estimate hazard ratios for coronary death, comparing individuals aged 55-64, 65-74, and >or=5 yrs with those aged <55 yrs. Adjustments were made for coronary risk factors to quantify their contributions to the age differential. RESULTS: During 4.1 million person-years of follow-up, there were 2,915 deaths from CHD. The risk of CHD increased substantially with age in all groups, especially in women. Differences in cardiovascular risk factors explained between one-quarter to one-third of the age-related excess of CHD in men and one-half of that in women. Systolic blood pressure was the chief contributor to the excess risk in all groups. CONCLUSIONS: Systolic blood pressure was the most important modifiable risk factor contributing to the excess CHD risk that occurs with aging in men and women, but in comparison with the effects of age itself, the effects of blood pressure are small.