Knowledge of the contribution of blood platelets and white and red thrombi in occlusive cerebrovascular disease and brain ischemia and infarction provides the present rationale for the use of antithrombotic treatment. There are now 4 general strategies for reducing the formtion of white platelet-fibrin clots: 1) administration of agents that affect platelets and the endothelium (dipridamole, cilostazol); 3) administration of agents that affect the attachment of platelets to fibrinogen (abciximab and other glycoprotein IIIb/IIIa inhibitors); and 4) reducing fibrinogen levels and activity. The clinical situations that require antithrombotic treatment vary. In patients in whom stents have been placed in coronary, peripheral, or brain-supplying arteries, agents acting predominantly on platelets have theoretical advantages. In patients with penetrating artery disease, agents with substantial endothelial effects have a theoretical advantage.