Since the consumption of wine in the United States has increased in recent years, a number of patients may be admitted to the hospital on the morning of their elective surgery after having consumed wine with dinner the evening before. Research indicates that by reducing platelet aggregation, moderate alcohol consumption can protect against the development of coronary artery disease. Therefore, an alcohol consumption in the night before surgery may influence on a patient's hemostasis. This study was designed to investigate the effects of wine intake the night before surgery on platelet aggregation and thromboelastogram in healthy volunteers. Twenty-four healthy subjects participated in this randomized crossover study. Each subject drank either a half bottle (300-350 ml, approximately two glasses) of red or white wine during dinner on two separate occasions. Blood samples were taken on the morning of the scheduled wine consumption and at the same time on the morning after the wine consumption. Platelet counts, and thromboelastogram (TEG) were performed and platelet function was assessed by adenosine diphosphate (ADP) and collagen induced platelet aggregation tests. There were no significant changes in platelet number, platelet function and TEG values the morning after wine consumption, and there were no significant differences in platelet number, platelet function and TEG values between red and white wine. This study indicates that an intake of red or white wine during dinner does not affect platelet number, platelet function, or viscoelastic properties of blood the next morning. A half bottle of red or white wine intake prior to a next day's elective surgery has no significant risk of suppression of coagulation function.