Abstract: This invention relates to novel cyclic compounds containing carbocyclic ring systems useful as antagonists of the platelet glycoprotein IIb/IIIa complex, to pharmaceutical compositions containing such cyclic compounds, with or without other therapeutic agents, and to methods of using these compounds, with or without other therapeutic agents, for the inhibition of platelet aggregation, as thrombolytics, and/or for the treatment of other thromboembolic disorders. This invention also relates to methods of using the cyclic compounds of the invention in combination with anti-coagulants such as warfarin or heparin, or additional anti-platelet agents such as aspirin, piroxicam or ticlopidine, or thrombin inhibitors such as boropeptides, hirudin or argatroban, or thrombolytic agents such as tissue plasminogen activator, anistreplase, urokinase or streptokinase, or combinations thereof, for the treatment of thromboembolic disorders. A representative compound of the invention is cyclo(D-Val-(.sup..alpha.