The effect of glucose on arginine-stimulated glucagon and insulin secretion was studied in perfused rat pancreas prepared by the modified method of Grodsky. The isolated rat pancreas was perfused with 4.5% dextran KRBB containing glucose over 60 minutes. Twenty minutes after the start of glucose perfusion, 5% arginine solution was injected during twenty minutes via a side arm at the rate of 0.2ml per minute. The increases of insulin and of glucagon in the effluent at the two minute period of arginine injection were 43.2±3.5 to 86.4±6.2ng/m/ and 40±3 to 510±21pg/ml, respectively, when the perfusate contained 300mg/d/ of glucose. They were 21.3±2.4 to 39.0±3.3ng/ml and 126±8 to 3433±127pg/ml, if the perfusate contained 150mg/dl of glucose, and 2.0±0.3 to 32.4±3.2ng/m/ and 525±18 to 2062±106pg/ml if the perfusate contained 50mg/dl of glucose, respectively. The perfusion of glucose free solution containing arginine provoked a slight increase in insulin (2.1±0.2 to 10.7±1.6ng/ml) and glucagon (625±23 to 745±46pg/ml). These results showed that glucose might be necessary for arginine stimulated glucagon and insulin secretion in the perfused rat pancreas.