One hundred fifty-five consecutive patients resuscitated after out-of-hospital ventricular fibrillation by a physician-manned advanced life support unit were randomly assigned to receive nimodipine or placebo at a dosage of 10 micrograms/kg as an intravenous injection immediately after restoration of spontaneous circulation, followed by an infusion of 0.5 micrograms/kg per minute for 24 hours. No significant difference was found in the 1-year survival rate of nimodipine-treated (30 [40%] of 75 patients) and placebo-treated patients (29 [36%] of 80 patients). Recurrent ventricular fibrillation during the treatment occurred in one patient in the nimodipine group compared with 12 patients in the placebo group. In a post hoc analysis of patients with very long delays in advanced life support (more than 10 minutes), the 1-year survival rate was higher with nimodipine (eight [47%] of 17 patients) than with placebo (two [8%] of 26 patients). Nimodipine may be of benefit in patients with delayed resuscitation.