In a series of 160 consecutive patients with pre-hospital ventricular fibrillation, outcomes were improved if base-station personnel precisely followed the initial 7 steps of standard VF algorithms. This improvement reached statistical significance regarding survival to hospital discharge (17% vs. 6%, P less than 0.05), and reflected a very strong trend with regard to initial resuscitation and admission to hospital (31% vs. 18%, 0.05 less than P less than 0.10). These measures of outcome were even more strongly related to field time, such that patients treated in the field for less than 15 min did far better than patients treated longer. While concordance with algorithms did not independently diminish field time in this study, this probably reflects the fact that paramedics had to establish base hospital contact and receive orders from base personnel in all patients; thus it is probable that allowing paramedics to treat patients in VF, using precise protocols, without prior communication with a base hospital, would diminish field time, and this might lead to even further improvement in patient outcome.