From 1933 to 1974, Portugal was governed by a political regime known as the Estado Novo (New State), which authoritatively upheld the principle of maintaining sound public finances. This paper accordingly sets out to test the sustainability of Portuguese fiscal policy during that period. Using tests for stationarity and cointegration, we find sufficient evidence that fiscal policy sustainability characterised the period of the Estado Novo as a whole. However, the onset of colonial warfare in 1961 may have marked a shift towards unsustainable fiscal policy