OBJECTIVE: Studies reporting an association between treatment delay and outcome for patients with ST segment elevation myocardial infarction (STEMI) have generally not included patients treated by a primary percutaneous coronary intervention (PPCI) service that systematically delivers reperfusion therapy to all eligible patients. We set out to determine the association of call-to-balloon (CTB) time with 30-day mortality after PPCI in a contemporary series of patients treated within a national reperfusion service.<br/> METHODS: We analysed data on 16 907 consecutive patients with STEMI treated by PPCI in England and Wales in 2011 with CTB time of ≤6 hours.<br/> RESULTS: The median CTB and door-to-balloon times were 111 and 41 min, respectively, with 80.9% of patients treated within 150 min of the call for help. An out-of-hours call time (58.2% of patients) was associated with a 10 min increase in CTB time, whereas inter-hospital transfer for PPCI (18.5% of patients) was associated with a 49 min increase in CTB time. CTB time was independently associated with 30-day mortality (p&lt;0.0001) with a HR of 1.95 (95% CI 1.54 to 2.47) for a CTB time of &gt;180-240 min compared with ≤90 min. The relationship between CTB time and 30-day mortality was influenced by patient risk profile with a greater absolute impact of increasing CTB time on mortality in high-risk patients.<br/> CONCLUSION: CTB time is a useful metric to assess the overall performance of a PPCI service. Delays to reperfusion remain important even in the era of organised national PPCI services with rapid treatment times and efforts should continue to minimise treatment delays.<br/>