The re-emergence of the public deficit in most industrialized countries, together with its persistence or refusal to fall, has awakened the interest of experts due to the economic effects of the different sources of financing public spending. One of the questions arising most frequently refers to the effects of the public deficit and stocks of public debt on national interest rates. This research examines to what extent long-term nominal interest rates are cointegrated with the public deficit in the period 1964-1993.