Computer-assisted static/dynamic renal imaging with [197Hg] chlormerodrin and [99mTc] pertechnetate was evaluated prospectively as a screening test for renovascular hypertension. Results are reported for 51 patients: 33 with benign essential hypertension and 18 with renovascular hypertension and for 21 normal controls. All patients underwent renal arteriography. Patients with significant obesity, renal insufficiency or renoparenchymal disease were excluded from this study. Independent visual analyses of renal gamma images and time-activity transit curves identified 17 of the 18 patients with renovascular hypertension; one study was equivocal. There were 5 equivocal and 3 false-positive results in the essential hypertension and normal control groups. The sensitivity of the method was 94%; the specificity, 85%. Since the prevalence of the renovascular subset of hypertension is approximately 5%, the predictive value is only 25%. Inclusion of computer-generated data did not improve this result. Accordingly, this method is not recommended as a primary screening test for renovascular hypertension.