Field identification and treatment of ST-segment elevation myocardial infarction (STEMI) by paramedics is an important component of care for these patients. There is a paucity of studies in the setting of paramedic-identified STEMI. This study investigated mortality and factors associated with mortality in a large state-wide prehospital STEMI sample. Methods: Included were adult STEMI patients identified and treated with reperfusion therapy by paramedics in the field between January 2016 and December 2018 in Queensland, Australia. 30-day and one-year all-cause mortality was compared between two prehospital reperfusion pathways: prehospital fibrinolysis versus direct referral to a hospital for primary percutaneous coronary intervention (direct percutaneous coronary intervention [PCI] referral). For prehospital fibrinolysis patients, factors associated with failed fibrinolysis were investigated. For direct PCI referral patients, factors associated with mortality were examined. Results: The 30-day mortality was 2.2% for prehospital fibrinolysis group and 1.8% for direct PCI referral group (p = 0.661). One-year mortality for the two groups was 2.7% and 3.2%, respectively (p = 0.732). Failed prehospital fibrinolysis was observed in 20.1% of patients receiving this therapy, with male gender and history of heart failure being predictors. For direct PCI referral group, low left ventricular ejection fraction (LVEF) on admission and cardiogenic shock prior to PCI were predictors of both 30-day and one-year mortality. Aboriginal and Torres Strait Islander status, and impaired kidney function on admission, were associated with one-year but not 30-day mortality. Being overweight was associated with lower 30-day mortality. Conclusions: Mortality in STEMI patients identified and treated by paramedics was low, and the prehospital fibrinolysis treatment pathway was effective with a mortality rate comparable to that of patients undergoing primary PCI. Key words: prehospital; Queensland; cardiac reperfusion; STEMI.