Background: The Time to Thrombolysis Substudy of the National Registry for Myocardial Infarction provided the opportunity to identify factors that delay thrombolytic treatment of patients with ST-segment elevation acute myocardial infarction. Participants: Forty-two participating registry hospitals volunteered for the Time to Thrombolysis Substudy. Methods: A case report form was developed to collect time points for emergency department arrival (door), recording of the electrocardiogram (ECG) (data), entry of the order to give a thrombolytic drug (decision), and initiation of the thrombolytic infusion (drug) as defined by the National Heart Attack Alert Program. The impact of mode of transportation to the hospital, sex, policy- driven cardiology consultation and/or contact of the primary care physician on door-to-drug time, and each component interval were determined in 1755 patients who were treated with recombinant tissue-type plasminogen activator (Alteplase). The t test was used for comparison of means and the nonparametric sign test was used for medians. Results: A minority of patients arrived at the hospital by ambulance, although more women (49.6%) arrived by ambulance than men (40.9%). However, women arrived at hospitals significantly later after onset of symptoms than men. It took half as long for patients arriving by ambulance to be seen by the physician than those who transported themselves to the hospital. It took longer for women to have the initial 12- lead ECG recorded than men. The decision to order a thrombolytic agent was delayed by 22 minutes and median door-to-drug time by 21 minutes in those patients who had a cardiac consultation over those in whom the drug was ordered and infusion was initiated by the emergency physician. Although the initial 12-lead ECG showed ST-segment elevation in 86% of patients who received the thrombolytic drugs, with no difference between men and women and no difference in the rate of cardiology consultation between men and women (77%), door-to-decision time and door-to-drug time were substantially longer for women having consultation than men. There was no significant difference in door-to-decision time between men and women when no consultation was performed, but it still took longer for a drug infusion to be initiated in women. Contacting the primary care physician delayed the decision to give a thrombolytic drug by 18 minutes and the administration of the drug by 20 minutes, but there were no differences between men and women. Preparation of the drug in the pharmacy resulted in significant delay compared with mixing it in the emergency department. Conclusions: Hospital practices and policies, including contacting the primary care physician prior to the initiation of a lytic drug, cardiology consultation, and preparation of the drug in the pharmacy rather than in the emergency department, significantly delay the goal of early treatment of patients with ST segment elevation acute myocardial infarction. Delays in hospital arrival for women are compounded by delays in the decision to treat them with a thrombolytic drug and initiation of the drug therapy in those women who receive consultation compared with men. Other delays in acquiring the first ECG and initiating the drug infusion in women are not explained.