We investigate the effects of public debt on economic growth and examine its viability as a policy tool to spur economic growth using a sample of 14 Middle Eastern and North African countries over the period 1980–2015. We reveal the existence of an inverted U-shaped relationship between public debt and economic growth that varies between oil and non-oil countries. Specifically, we find that the debt threshold hovers around 90% for oil countries and 45% for non-oil countries. Moreover, we show that public debt appears to more beneficial to non-oil countries regardless of its level vis-a-vis the threshold. Indeed, below the debt threshold, the marginal positive effects of public borrowings on economic growth are larger for non-oil countries. Similarly, above the debt threshold, the negative effects of debt on economic growth are lower for this group of countries. Our findings are critically important for policymakers and demonstrate the importance of a country’ energy endowment in moderating the relationship between debt and economic growth.