Current guidelines recommend a goal of door-to-balloon (D2B) time < 90 min for patients undergoing primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI). We aim to prospectively determine the effect of data feedback on D2B time and its seven individual components in primary PCI. From December 7, 2007, to June 2, 2009, 116 consecutive patients with STEMI who received PCI within 12 h of symptom onset were enrolled, including 56 patients before and 60 patients after the implementation of data feedback on July 28, 2008. The proportion of patients treated within 90 min increased from 26.8 to 55.0% (p = 0.002). On multivariable analyses, data feedback (OR 5.3, p = 0.003), known coronary artery disease (OR 5.6, p = 0.043), regular hours presentation (OR 3.3, p = 0.048), and arrival by transfer (OR 14.0, p = 0.003) were independent predictors of a D2B time less than 90 min. Median D2B time decreased from 112 min before data feedback to 87 min after data feedback (p < 0.001). The most significant decrease occurred in median door-to-ECG (11 vs. 3 min, p < 0.001), consult-to-cardiologist (5 vs. 3 min, p < 0.001), and puncture-to-balloon (21 vs. 17 min, p = 0.004) time. Data feedback to the emergency department and catheterization laboratory staff decreases D2B time in primary PCI. This simple approach may be the best first step to decrease D2B time in hospitals that are still striving to achieve the goal of D2B time < 90 min.