[en] In 1928, the Swedish geneticists Hermann Nilsson-Ehle and Ake Gustafsson initiated experiments with induced mutations using a diploid barley species. The experiments started with X-rays and UV-irradiations, soon the first chlorophyll mutations were obtained followed by the first viable 'Erectoides' mutations. Several other valuable mutants were isolated: high-yielding, early maturity, lodging resistance and with changed ecological conditions. The X-ray experiments were then expanded with different pre- and after treatments, and using other types of irradiation. Neutrons, positrons etc, were used and finally chemical mutagenes, starting with mustard gas and concluding with the inorganic sodium azide. This research brought a wealth of observations of general biological importance, high increased mutation frequencies, differences in the mutation spectrum and the ability to direct mutagenesis of specific genes. This Scandinavian mutation research was non-commercial although some mutants have become agronomically valuable. Its peaks of activities were during the fifties, sixties and seventies. Barley has been the main experimental material, but other species were also included in the program. About 10 000 different mutants with a broad variation were collected and several mutant characteristics have been analyzed in more detail genetically and with regard to mutagen specificity. Among these mutant groups most effort has been concentrated on the three following ones: (1) Early maturity mutants. At an early stage it was established that the time for early heading and maturity could easily be changed by mutagenesis. 9 different mat loci could be identified among the drastic type of earliness. One of these loci mat-a proved to be very striking, it is photo- and thermo-period insensitive. It causes a profound change in photoperiod reaction, making the mutant heading even in short days, and it became important for breeding. (2) Six-row and Intermedium mutants. Two-row barley can be mutated in a single step to six-row barley and this affects the development of the lateral spikelets. All 41 Swedish mutants have been localized to one single locus, hex-v. But two-row barley can also produce spike development intermediate between the two- and six-row state. 11 different int loci could be determined and were studied in more detail. (3) Mutants affecting surface waxes. The epicuticular wax coating has a very complex genetic architecture and affects the presence and type of waxes on three different organs (spike, leaf sheath and leaf blade). In total 1580 mutants have been localized to 79 different cer gene loci. Seven different types of mutagenic agents have been applied, and a great range of mutability was found. (author)