Current guidelines recommend patients with ST-elevation myocardial infarction receive primary percutaneous coronary intervention (PCI) within 90 minutes of admission, although there are conflicting data regarding the relation between time to treatment and mortality in these patients. We used logistic regression analyses employing a fractional polynomial model to evaluate the association between door-to-balloon time and 1-year mortality in patients with ST-elevation myocardial infarction > or =65 years old undergoing primary PCI from 1994 to 1996 (n = 1,932). Median door-to-balloon time was 128 minutes (interquartile range 92 to 178, 24.2% treated within 90 minutes). Overall 1-year mortality was 21.1%. Longer door-to-balloon times were associated with higher 1-year mortality in a continuous, nonlinear fashion (30 minutes 10.9%, 60 minutes 13.6%, 90 minutes 16.5%, 120 minutes 19.5%, 150 minutes 22.5%, 180 minutes 25.3%, 210 minutes 27.9%). The nature of the association between door-to-balloon time and 1-year mortality was best modeled by a second-degree fractional polynomial (p <0.001). Findings were similar after multivariable adjustment as any increase in door-to-balloon time was associated with successive increases in patients' 1-year mortality (30 minutes 8.8%, 60 minutes 12.9%, 90 minutes 16.6%, 120 minutes 19.9%, 150 minutes 22.9%, 180 minutes 25.5%, 210 minutes 27.7%). In conclusion, any delay in primary PCI is associated with increased 1-year mortality, suggesting efforts should focus on decreasing time to treatment as much as possible, even among those centers currently providing primary PCI within 90 minutes.