OBJECTIVES: Coronary heart disease (CHD) mortality has declined substantially in Canada over recent decades.  Our objective was to determine what proportion of this decline was associated with temporal trends in CHD risk factors and advancements in medical treatments. METHODS: The validated IMPACT model was used for all analyses, integrating data on population size, CHD mortality, in addition to risk factor and treatment uptake changes in adults 25 years and older between 1994 and 2005 in Ontario. Relative risks and regression coefficients from the published literature quantified the relationship between CHD mortality and a) evidence-based therapies in 8 distinct CHD sub-populations (acute myocardial infarction (AMI), acute coronary syndromes, secondary prevention post-AMI, chronic angina/CHD, in-hospital, heart failure, community heart failure, and 1° prevention for hyperlipidemia or hypertension) and  b) population trends in 6 risk factors (smoking, diabetes mellitus, systolic blood pressure, plasma cholesterol, exercise, and obesity).   The outcome of interest was the number of deaths prevented or postponed. RESULTS: From 1994-2005, the age-adjusted CHD mortality rate in Ontario fell 35% from 190.9 to 124.8 deaths per 100,000 inhabitants, translating to an estimated 7585 fewer CHD deaths in 2005.  Improvements in medical treatments accounted for approximately 43% of the total mortality decrease, most notably in AMI (9%), chronic angina (17%) and community heart failure (10%).  Trends in risk factors explained approximately 48% % of the total mortality decrease, specifically reductions in plasma cholesterol (23%), and systolic blood pressure (20%).  Increasing diabetes prevalence and body mass index had a negative impact, increasing CHD mortality by approximately 6% and 2%, respectively. CONCLUSIONS: Our results suggest that future CHD strategies should maximise evidence-based therapies and support more aggressive policies to promote healthy diets.