The binding of Fgn to GPIIb / IIIa has confirmed that there are two distinct amino acid sequences within the Fgn molecule that are responsible for mediating its attachment to GP IIb / IIIa receptor. In addition to monoclonal antibodies, the binding function of GP IIb / IIIa can be blocked by synthetic small peptides containing the RGD and APLRV sequence. In our preliminary study it was found that besides inhibition of platelet aggregation and thrombus formation RGDS showed vasodilation effects as well. In an attempt to confirm the vasodilation effect of RGDS related peptides, RGDF, APLRV, APLRVRGDS and APLRVRGDF were investigated. The effects of these synthetic peptides on rat aortic strips pretreated with NE in vitro were observed. The relaxing extents of contracted strips for the peptides at three doses (10 5 mol / L, 10 6 mol / L and 10 7 mol / L) were recorded.