Genetic variability for tolerance to mineral toxicities, and in particular to aluminum and manganese in acid soils, occurs in a number of crops, and has been widely exploited in wheat. Screening techniques in both the laboratory and the field are reviewed and the mode of inheritance to tolerance is indicated for a number of wheat varieties. In several cases a single dominant gene is involved which can be easily and rapidly transferred into otherwise well adapted varieties. Different genes may be involved for tolerance to different levels of toxicity, and to different toxic minerals. Tolerant varieties are now grown widely in many parts of the world making production possible where none was possible before or increasing production in areas which were previously considered to be marginal.