Fifty-seven patients with cervical bruits and abnormal ocular pneumoplethysmography but without symptoms were followed prospectively. Mean follow-up was 32 months and all patients were followed for at least 1 year. Twenty-nine patients consented to join a randomized study comparing treatment with aspirin, close follow-up, and no intervention unless symptoms developed [( NI: ASA] n = 14) versus intervention with arteriography and prophylactic surgery [( I: A/S] n = 15). Among patients who refused randomization, 14 were treated with NI: ASA and 14 with I: A/S. Endpoints for analysis included all unfavorable outcomes related to both management plans and included stroke, death of stroke, major angiographic and perioperative complications, asymptomatic carotid occlusion, and recurrent carotid artery stenosis. In both the randomized and nonrandomized portions of the study unfavorable outcomes were more frequent in patients treated with I: A/S, and by combining the results of both studies a significant difference was observed (N: ASA - 3.6% versus I: A/S - 31%; X:2 = 4.78; p less than 0.05). Among patients treated with NI: ASA, a single minor stroke occurred without warning. In patients from all groups who underwent arteriography, advanced carotid stenosis was found in 78% (mean percent diameter stenosis = 72% +/- 2%; mean residual lumen = 1.3 +/- 0.1 mm). We conclude that, despite the probability of underlying severe carotid stenosis, most patients with cervical bruit and abnormal ocular pneumoplethysmography but without symptoms are appropriately managed without intervention unless symptoms develop.