The Irish Famine killed over a million people who would not have died otherwise. The nosologies published by the 1851 Irish census provide a rich source for the causes of death during these catastrophic years. This source is extremely rich and detailed, but also inaccurate and deficient to the point where many scholars have given up using it. In this article we try to make adjustments to the death-by-cause tabulations and provide more accurate ones. These tables are then used to analyse the reasons why so many people died and why modern famines tend to be less costly in terms of human life.