Thirty-two patients who had open heart surgery at Kyugpook National University hospital from October 1984 to February 1985, were studied for blood glucose level at 30 minutes after anesthetic induction, at the time of total bypass, on partial bypass, and 1 hour after bypass. Also these values were studied in relation to various disease entities such as A(V)SD, TOF and M(A)S(I) groups. The results were as follows. The values of the control group(30minute after anesthetic induction.) were 104.6+/-21.98mg%, those at the end of total bypass were 213.7+/-42.52mg%, those at the end of partial bypass were 239.5+/-59.95mg%, and the values 1 hour after bypass were 201.9+/-45.51mg%. The values at the end of total and partial bypass were significantly increased compared with those at 30minute after anesthetic induction(p<0.50). Among the disease groups, TOF group had a tendency for a more elevated blood glucose level than the othe groups(A(V)SD, M(A)S(I)). When the bypass extended beyond 90 minutes the blood glucose level was higher than in those under bypass for less than 90 minute.