Objectives: To assess whether a collaborative interdepartmental pathway involving emergency department (ED) physicians activating the cardiac catheterisation laboratory (CCL) with immediate patient transfer to the CCL reduces door‐to‐balloon (DTB) times for patients with suspected ST‐elevation myocardial infarction (STEMI). Design, setting and participants: A quasi‐experimental before‐and‐after observational study using a prospective database, supplemented by chart review, of consecutive patients transferred from the ED to the CCL for suspected STEMI, from January 2007 to October 2009, at Sir Charles Gairdner Hospital, an adult tertiary‐care hospital, Western Australia. Main outcomes measures: Median DTB time and proportion of patients with DTB time of < 90 minutes. Secondary outcomes, based on analysis of predefined subgroups, included door‐to‐activation time, activation‐to‐balloon time and false‐positive activations of the CCL. Results: Two hundred and thirty‐four patients underwent emergency coronary angiography for suspected STEMI, with 188 (80%) undergoing percutaneous coronary intervention (118 before and 70 after implementation of the new pathway). Following implementation of the new pathway, median DTB time reduced from 97 to 77 minutes (P < 0.001), median door‐to‐activation time from 28 to 15 minutes (P = 0.002) and median activation‐to‐balloon time from 66 to 53 minutes (P < 0.001). The proportion of patients with recommended DTB time of < 90 minutes increased from 41% to 77% (P < 0.001) with no change in false positive CCL activation rates (12% v 11%; P = 0.38). Conclusion: ED physician activation of CCL with immediate patient transfer is associated with highly significant improvements in DTB time without increased false positive rates.