Background Mortality from out-of-hospital cardiac arrest (OHCA) is characterized by substantial regional variation. The Institute of Medicine (IOM) recently recommended enhancing the capabilities of EMS systems to improve outcome. In this study, we analyzed the trend in outcome from ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT) OHCA in Rochester, MN. Survival from these forms of arrest is commonly employed as a benchmark of Emergency Medical Services (EMS) system performance. Methods Using a population-based Utstein-style registry in Rochester, MN where a first responder early defibrillation system is utilized, we evaluated outcome from all EMS-treated VF/pVT arrests and the subgroup of bystander-witnessed VF/pVT from 1991 to 2016. Outcome measurement was neurologically intact survival to discharge, defined as Cerebral Performance Category (CPC) 1 or 2. We divided the 26-year study into three periods: 1991–1997, 1998–2008, and 2009–2016, based on initiation of the first responder system of police officers in 1991 and fire-rescue personnel in 1998, and the latter period for comparison with our previous report in 2009. Results We observed 355 all VF/pVT arrests and 292 bystander-witnessed VF/pVT arrests between 1991 and 2016. In 2009–2016, neurologically intact survival to discharge from overall VF/pVT and bystander-witnessed VF/pVT increased to 53.7% and 65.2%, respectively, compared with 39.5% and 43.4% in 1991–1997. Using multivariable analysis, survival significantly increased in 2009–2016 among all VF/pVT arrests (adjusted OR, 3.10; 95% CI, 1.54–6.40) and bystander-witnessed VF/pVT (adjusted OR, 4.28; 95% CI, 2.01–9.50), compared with those in 1991–1997. Conclusions We observed a significant improving secular trend in neurologically intact survival from VF/pVT cardiac arrests with a relatively high recent survival rate in this EMS System.