Pinane-thromboxane A2 (PTA2, [1alpha,2 beta(Z),-3 alpha (1E,3R*),5 alpha]-7-(3-(3-hydroxy-1-octenyl)-6,6-dimethylbicyclo[3.1.1]hept-2-yl)-5-heptenoic acid) has been synthesized and tested for biological activity in systems responsive to thromboxane A2, stable prostaglandin endoperoxide (PGH2) analogs, and prostatacyclin (PGI2). At low concentrations, PTA2 inhibited cat coronary artery constriction induced by stable prostaglandin endoperoxide analogs, and it stabilized liver lysosomes. At slightly higher concentrations, it inhibited platelet aggregation. At still higher concentrations, PTA2 inhibited thromboxane synthetase, but it had no effect on prostacyclin synthetase. The analog also had no effect on the inhibition of platelet aggregation by PGI2 or prostaglandin D2. It is suggested that PTA2 has a suitable biochemical profile for use as an antithrombotic agent.