Mortality rates from different cancers in migrants to Argentina from II individual countries and 6 groups of countries were compared with those in the Argentina-born population and their countries of origin. Almost all countries of origin had higher mortality rates from gastric cancer than Argentina, but the risk declines in migrants, and for European migrants becomes similar to that of the Argentina-born. In contrast, mortality from oesophageal cancer is significantly lower in European countries than in Argentina. For cancer of the colon and breast, most countries have lower mortality rates than the Argentina-born, the exceptions being Uruguay and Germany, and migrants demonstrate a convergence of risk towards that of Argentina-born. These results suggest that migrants to Argentina undergo changes in some environmental exposure, probably dietary, which give rise to substantial alterations in cancer risk within their lifespan.