Background: Guidelines for patients with ST-elevation myocardial infarction include a door-to-balloon time (DTBT) of =90min for primary percutaneous coronary intervention. Aim: The aim of this study was to assess temporal trends (2006-2010) in DTBT and determine if a reduction in DTBT was associated with improved clinical outcomes. Methods: We compared annual median DTBT in 1926 STEMI patients undergoing primary percutaneous coronary intervention from the Melbourne Interventional Group registry. ST-elevation myocardial infarction presenting >12h and rescue percutaneous coronary intervention was excluded. Major adverse cardiac events were analysed according to DTBT (dichotomised as =90min vs >90min). A multivariable analysis for predictors of mortality (including DTBT) was performed. Results: Baseline demographics, clinical and procedural characteristics were similar in the STEMI cohort across the 5 years, apart from an increase in out-of-hospital cardiac arrest (3.6 in 2006 vs 9.4 in 2010, P <0.0001) and cardiogenic shock (7.7-9.6 , P = 0.07). The median DTBT (interquartile range) was reduced from 95 (74-130) min in 2006 to 75 (51-100) min in 2010 (P <0.01). In this period, the proportion of patients achieving a DTBT of =90min increased from 45 to 67 (P <0.01). Lower mortality and major adverse cardiac event rates were observed with DTBT =90min (all P <0.01). Multivariable analysis showed that a DTBT of =90min was associated with improved clinical outcomes at 12 months (odds ratio 0.48; 95 confidence interval 0.33-0.73, P <0.01). Conclusion: There has been a decline in median DTBT in the Melbourne Interventional Group registry over 5 years. DTBT of =90min is associated with improved clinical outcomes at 12 months.