The value of electropharmacological testing in patients (pts) with sustained ventricular tachyarrhythmias was studied in 46 consecutive pts (24 with sustained ventricular tachycardia (SVT) and 22 with cardiac arrest due to a ventricular tachyarrhythmia. Forty-two pts underwent a baseline electrophysiological study. The ventricular stimulation protocol included up to 3 extrastimuli during spontaneous rhythm and during paced ventricular rhythm at 100/min, 130/min, 160/min and brief bursts pacing at 2 ventricular sites. Ventricular tachycardia was induced in 37/42 pts (88%) (sustained in 32 pts and non sustained in 5 pts). Twenty nine pts underwent 79 trials of different drug regimens (mean 2.72 per pt, range 1-8). A totally successful drug regimen was found in 15/29 pts (51.7%) and a partially successful drug regimen in 11/29 pts (37.9%). Twenty-three pts were discharged on a drug regimen successful during serial electropharmacological testing (Group I) and 23 pts were discharged on an empiric drug regimen (Group II). Each pt was followed-up for a mean period of 15 months (range 1-74). Group I pts had fewer arrhythmia recurrence (SVT and/or sudden death) than Group II pts (2/23 vs 13/23 p less than 0.01). In conclusion electropharmacological testing is an useful tool in the therapy of pts with sustained ventricular tachyarrhythmias.