Abstract
A marked increase in platelet adhesiveness was shown to occur within four hours of operation. Postoperative red cells produced greater adhesiveness in platelets from a common pool than did preoperative red cells. A greater increase in platelet adhesiveness was observed following operation with the whole blood technique than when exogenous adenosine diphosphate was added to platelet-rich plasma. Release of adenosine diphosphate from red cells so facilitated may contribute to the acute platelet-adhesiveness response to operation.