This is a report of a multicenter open study of the use of tocainide, a new lidocaine-like antiarrhythmic with a high oral bioavailability, in the treatment of life-threatening ventricular arrhythmias refractory to other therapy. The majority of patients have received 1,200 to 2,400 mg daily in divided doses and have been treated for over 6 months and some for longer than 3 years. Overall, 61% of the patients responded successfully to tocainide therapy. In the 252 patients with documented, severe, symptomatic arrhythmias, 71% responded, and the majority (87%) showed a total abolition of symptomatic events. Gastrointestinal and central nervous system events were the most common adverse experiences, and 11% had to discontinue therapy; however, the remaining 89% tolerated tocainide satisfactorily.