We investigated in 449 patients with severe carotid arterial disease, who did not undergo revascularization, the incidence of new stroke or new myocardial infarction (MI) or death in patients treated with statins (66%) and in patients not treated with lipid-lowering therapy (34%). Hypercholesterolemia was present in all of the 298 patients (100%) treated with statins and in 145 of 151 patients (96%) not treated with statins (p = 0.001). Follow-up was 26 ± 18 months in patients treated with statins and 21 ± 17 months in patients not treated with statins (p <0.0001). New stroke or new MI or death occurred in 45 of 298 patients (15%) treated with statins and in 102 of 151 patients (68%) not treated with statins (p <0.0001). Stepwise Cox regression analysis showed that significant independent prognostic factors for time to development of new stroke or new MI or death were use of statins (risk ratio 0.13, p <0.0001), smoking (risk ratio 1.45, p = 0.0329), systemic hypertension (risk ratio 1.81, p = 0.0011), diabetes mellitus (risk ratio 2.87, p <0.0001), previous stroke (risk ratio 3.18, p<0.0001), and previous MI (risk ratio 2.15, p <0.0001). In conclusion, statins decrease the incidence of new stroke or MI or death in patients with severe carotid arterial disease who do not undergo revascularization.