Thirty-two patients received flecainide acetate for nonsustained ventricular tachycardia after having had unsuccessful treatment with a mean of four antiarrhythmic drugs. The mean left ventricular ejection fraction was 41% in 27. Thirty-one patients had organic heart disease, and 22 patients had arrhythmia-related symptoms. Total suppression of ventricular tachycardia occurred in 22 patients. Thirty patients were discharged from the hospital receiving flecainide at a mean (±SD) dosage of 315 ± 76 mg/d and 26 of these patients attained a mean trough plasma drug level of 567 ± 254 ng/mL. One patient had proarrhythmia and 3 had worsening of heart failure. Twenty-two patients remained in the trial for a mean follow-up of 13 ± 7 months. Five patients died (1 suddenly) during the follow-up period. Our data indicate that flecainide suppresses refractory nonsustained ventricular tachycardia in 69% of patients who have organic heart disease. Serious adverse effects were minimized by initiation of treatment in the hospital and careful surveillance of electrocardiograms and plasma drug levels.