In this study, we investigated the effect of DMSO, a highly dipolar organic liquid, in collagen ($5{mu}g/ml$)-stimulated platelet aggregation. DMSO inhibited platelet aggregation at 0.5% by inhibiting production of thromboxane $A_2$ ($TXA_2$) which was associated with blocking cyclooxygenase (COX)-1 activity and $TXA_2$ synthase. In addition, DMSO significantly increased the formation of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP) and cyclic guanosine monophosphate (cGMP) from guanosine triphosphate (GTP). On the other hand, DMSO (0.1~0.5% concentration) did not affect the LDH release which indicates the cytotoxicity. Based on these results, DMSO has anti-platelet effect by regulation of several platelet signaling pathways, therefore we suggest that DMSO could be a novel strategy on many thrombotic disorders.