© 2018 Elsevier Inc. Primary ventricular fibrillation (PVF) is a dreadful complication of ST segment elevation myocardial infarction (STEMI). Scarce data are available regarding PVF prognosis since primary percutaneous coronary intervention (PPCI) became routine practice in STEMI. Our aim was to compare 30-day and 1-year mortality for patients with and without PVF (including out-of-hospital and in-hospital PVF) within a regional registry of PPCI-treated STEMI patients. This prospective multicenter registry included all consecutive STEMI patients treated with PPCI from January 2010 to December 2014. Patients were classified as non-PVF or PVF, with further subdivision into out-of-hospital and in-hospital PVF. We analyzed 30-day and 1-year all-cause mortality in groups. The registry included 10,965 patients. PVF occurred in 949 patients (8.65%), including 74.2% out-of-hospital and 25.8% in-hospital PVF. Compared with the non-PVF group, PVF patients were younger; less commonly diabetic; more frequently had anterior wall STEMI, higher Killip–Kimball class, and left main disease; and showed significantly higher 24-hour (5.1% vs 1.1%), 30-day (18.5% vs 4.7%), and 1-year mortality (23.2% vs 7.9%) (all p <0.001). Mortality did not differ in out-of-hospital versus in-hospital PVF. After multivariable adjustment, PVF remained associated with all-cause 30-day (2.32, 95% CI: 1.91 to 2.82, p <0.001) and 1-year (HR: 1.59, 95% CI: 1.13 to 2.24, p = 0.008) mortality. In conclusion, we present the largest registry of PVF patients in the era of routine PPCI in STEMI. Although overall STEMI mortality has declined, PVF emerged as a predictor of both 30-day and 1-year mortality. These data warrant prospective validation and proper identification and protection of high-risk patients.