OBJECTIVE: To evaluate the relationship between how much a new cardiovascular therapy improves clinical outcomes over current therapies and how much more it can cost while still remaining 'economically attractive'. DESIGN: We developed a decision model to predict the 6-month cumulative cost savings and increased life expectancy that could be associated with new therapies for patients with non-ST elevation acute coronary syndrome. SETTING: This modelling study used outcome and cost data from US sources. METHODS: Event probabilities at 30 days and 6 months were estimated from US patients with non-ST elevation in the Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes (GUSTO) IIb trial; cost estimates were derived from patients enrolled in the Economics and Quality of Life substudy of this trial. Patient life expectancy estimates were calculated using survival estimates for similar patients treated at Duke University Medical Center. RESULTS: We found that new therapies costing up to $US2000 per episode that reduce 6-month mortality by 0.5%, death and nonfatal myocardial infarction (MI) by 1%, or death, nonfatal MI and revascularisation by 3%, may be cost effective by current standards. When new therapies costing up to $US1000 per episode reduce the absolute rate of death, nonfatal MI and revascularisation at 6 months by 6.5% or more, they may be cost saving. CONCLUSION: Our analysis suggests that economic constraints should not inhibit the development of effective new therapies.