It is a well known fact that the best method of determinign need ofr transfusion is the accurate measurement of blood loss related to the patient's status and surgical maneuvers during operation. There are many complications of blood transfusion and their pathophysiologic mechanism, and theprevention and management has been discussed. Among the complications of blood transfusion, urticaria is the most common symptom. The pathophysiologic mechanism of urticaria is understood in some degree at the present time but there are many different opinions as to its prevention and management. Furthermore antihistamine has been widely used for the prevention of urticaria but there are many debatable events about the use of antihistamine. This study was undertaken to investigate the recent reports concerning the use of antihistamine for the prevent in and management of urticaria. Two hundred eighty eight transfused patients among the total of six thousand four hundred forty eight surgical cases done at the Hanyang University hospital from January 1st to December 31th 1983. were reviewed. The result are as follows: 1) The incidence of urticaria was 28 cases (9.72%) among the 288 transfused cases and there was no sex difference. 2) The age distribution was 10 cases (12%) in the 2nd decade and 9 cases(11.3%) in the 4th decade. 3) The lowest incidence of urticaria was 5 cases (5.3%) with A blood type and high of incidence with B, O and AB blood type. 4) The physical status of class 3 was seem in 10 cases(43.5%) as the most common occurrence of urticaria. 5) The highest incidence of urticaria was observed in 9(45%) of 20 obstetric cases. 6) There was no significant differnece of urticaria incidence between the groups which did and did not use antihistamine. Also in the group which received histamine 10 minutes before treansfusion there was a significant decreases 6 cases (3.41%) among the 178 transfused cases. 7) There was no significant statistical difference between blood loss and transfused blood volumes. 8) There was no significant statistical change in the mean values of hemoglobin and hematocrit which were measured preoperatively, in recovery room and 24 hours after operation. 9) In the patient's who were tranfused with more than 10 oints of whole blood, urticaria developed in 9 cases (50%) among 18. From the results of this study, I consider the most effective method for the prevention of urticaria to be the administration of histamine 10 minutes before transfusion. Further investigation of this method will be carried out.