Barbara McClintock (1902-1992). Nobel Prize in Medicine and Physiology in 1983 «for her discovery of mobile genetic elements». She completely transformed the cytogenetics by studying the pigmentation of the corn grains. Her discovery of mobile genetic elements is of profound importance for the understanding of the organization, function and regulation of genes. She carried out her research alone and at a time when her contemporaries were not yet able to realize the generality, significance and implications of her findings. Her story illustrates the difficulties that female researchers have had historically.