Stroke 2004，Oct 28 Background and Purpose--Previously published meta-analyses exploring the effect of statins on stroke incidence included 20 000 patients and found a 2% to 30% risk reduction. It is not clear whether this is attributable to low-density lipoprotein-cholesterol (LDL-C) reduction. Statin trials have now included >90 000 patients. We have determined the effect of statins and LDL-C reduction on stroke prevention Summary of Review--We performed a systematic review and meta-analysis of all randomized trials testing statin drugs published before August 2003. The trials were identified using a computerized PubMed search. We analyzed separately statin effect on incident strokes and on carotid intima-media thickness (IMT) according to LDL-C reduction. The relative risk reduction for stroke was 21% (odds ratio [OR]， 0.79 [0.73 to 0.85])， with no heterogeneity between trials. Fatal strokes were reduced but not significantly： by 9% (OR， 0.91 [0.76 to 1.10]). There was no increase in hemorrhagic strokes (OR， 0.90 [0.65 to 1.22]). Statin size effect was closely associated with LDL-C reduction. Each 10% reduction in LDL-C was estimated to reduce the risk of all strokes by 15.6% (95% CI， 6.7 to 23.6) and carotid IMT by 0.73% per year (95% CI， 0.27 to 1.19). Conclusions--Statins may reduce the incidence of all strokes without any increase in hemorrhagic strokes， and this effect is mainly driven by the extent of between-group LDL-C reduction. Carotid IMT progression also strongly correlated with LDL-C reduction.