This invention pertains generally to prostacyclin analogs and methods for their use in promoting vasodilation, inhibiting platelet aggregation and thrombus formation, stimulating thrombolysis, inhibiting cell proliferation (including vascular remodeling), providing cytoprotection, preventing atherogenesis and inducing angiogenesis. Generally, the compounds and methods of the present invention increase the oral bioavailability and circulating concentrations of treprostinil when administered orally. Compounds of the present invention have the following formula: