In recent years, a number of studies have attempted to investigate the impact of federal budget deficits on the rate of interest. Studies by Evans [6; 7], Makin [13], Hoelscher [9; 10], Barth, Iden and Russek [2; 3], Dwyer [5], Cebula [4], among others, have analyzed this issue but have provided conflicting evidence on the impact of federal budget deficits on the rate of interest. This is due in part to differences in methodology, definition of budget deficit variables, sample period, and estimation techniques. Hoelscher [10], Barth, Iden, and Russek [2; 3], Feldstein and Eckstein [8] find that budget deficits affect interest rates, but Evans [6; 7], Makin [13], and Hoelscher [9], conclude that budget deficits have no significant effect on interest rates. The contributions of this paper are: first, to directly introduce, within the framework of rational expectations models, federal budget deficit and monetary variables. This technique of analyzing the impact of deficits on interest rates may shed new light on this important issue which has not appeared in the literature. Second, the deficit measure employed in this study is designed in a manner that it avoids being contaminated by changes in expenditures and tax receipts due to the automatic stabilizing aspects of fiscal policy. Third, it is explicitly recognized that monetary and fiscal policies jointly interact in determining interest rates. Finally, the policy process determining the interest rate is tested for stability over time. This is important in light of Evans's [6] work, who finds various episodes in the U.S. history when budget deficits increased for a few years but had no appreciable impact on interest rates. The intention in this paper is to investigate the reaction of economic agents who find that budget deficits may persist for a longer time in the future.