The four studies reported describe tolerance of high manganese (Mn) in solution culture for 164 wheat genotypes. The genotypes were mainly South American, Australian, and CIMMYT in origin. The aims were to identify sources of tolerance of Mn, to assess the possibility of breeding for tolerance, and to identify any mechanism of tolerance. Fourteen genotypes were tolerant of the highest stress used in our experiments (either 2184 or 3276 μM Mn in solution). These genotypes were from Australia, Mexico, Brazil, Chile and other South American countries. They did not display toxicity symptoms and their total dry matter yields were not reduced on exposure to Mn in solution culture. Conversely, the very sensitive cultivar, Teal, had yield reductions up to 87%. The mechanism of tolerance appeared to be internal tissue tolerance. Tolerant genotypes in Experiment 1 accumulated high concentrations of Mn in leaves (1961 μg kg‐1) and roots (3202 μg kg‐1) with no ill effects. The tolerance character appeared to be simply inherited, because it was readily traced through tolerant genotypes which were related. Where toxic effects of Mn were induced, shoot concentrations of calcium (Ca), potassium (K), and magnesium (Mg) were lowered and root/shoot weight ratios were decreased because of greater decrease in root weight than shoot weight.