This publication presents the scientific results obtained under the FAO/IAEA Co-ordinated Research Programme on Improvement of Cereals in Latin America through Mutation Breeding. Some of the selected mutants were already tested in multilocation trials and had higher yields and/or other advantages, in comparison with the leading local varieties. On the basis of these results it it expected that a few new mutant varieties of rice (Brazil, Costa Rica, Cuba, Guatemala), wheat (Brazil, Chile) and barley (Peru) will be officially released within the next few years. Still more mutants, which are valuable for conventional breeding programmes as new sources of desired genes, were selected. Refs, figs and tabs.