The right ventricular isolation procedure was developed to treat medically refractory, nonischemic right ventricular tachycardia. The effect of this procedure on regional myocardial blood flow to the isolated right ventricle was evaluated in 10 adult mongrel dogs. There were no significant changes in aortic pressure, right ventricular systolic or diastolic pressure, or cardiac index following right ventricular isolation when the left ventricle and right ventricular free wall were synchronously paced. Myocardial blood flow to the isolated right ventricle was unchanged following the procedure (0.85 ± 0.07 ml/min/gm to 0.87 ± 0.08 ml/min/gm; p = not significant). Analysis of regional flow revealed that only a thin rim of right ventricular tissue near the ventriculotomy showed a significant decrease in blood flow (1.10 ± 0.1 ml/min/gm to 0.29 ± 0.04 ml/min/gm; p > 0.05). Thus, this procedure leaves intact the blood supply to the great percentage of the right ventricular free wall. This finding supports the concept that the right ventricular isolation procedure is effective in isolating abnormal electrical activity without compromising regional myocardial blood flow.