In order to know the effect of 70% alcohol pretreatment for 3 weeks on the tissue rejection after tracheal homografts, window-type tracheal grafts were done on the ten mongrel dogs(horizontal length : 1cm, vertical length : 3 cartilage rings). 1st group(2 dogs) ;control(replantation) group. 2nd group(4 dogs) ; homograft group. 3rd group(4 dogs) ; homograft with 70% alcohol pretreatment. After examination about the presence of tracheal cartilage and restoration of the lining epithelium were done. External diameter, area, and perimeter of the graft site were measured by using image analyzer. 1) In the replantation group, grafted tracheal cartilage was noted without absorption. In the homograft group and homograft with 70% alcohol pretreatment group, tracheal cartilage was not present. Lining epithelium was present in all groups. 2) Decrement of the external diameter, area, and perimeter of the homograft group and homograft with 70% alcohol pretreatment group was prominent comparing to those of the replantation group. Therefore, 70% alcohol pretreatment of the graft material for 3 weeks did not prevent tissue rejection in the tracheal homograft in the canine.