This research work investigated the impact of external debt on the Gross Domestic Product of Nigeria, data covering the period 1981-2014 was analyzed using the E-View Econometric tool. It was found out that External Debt Stock (EDS) was negatively related to GDP. This implies that, as EDS rises GDP falls, perhaps due to the fact that such monies were misappropriated or not spent on social infrastructures that could improve the wellbeing of the people and enhance the growth rate of GDP. Exchange rate also has a positive impact on GDP, which may imply availability of a favorable exchange for export. Debt service payments and interest rate are insignificant, It is therefore recommended that external debt stock should be expended on Infrastructural facilities like machinery and equipments that will improve output and GDP, furthermore, debts service payments should be as at when due to avoid debt accumulation, Government should avoid financing long term project with short term loans.