The radiation (³²P) induced dwarf mutant of spring barley,Hordeum vulgare L., Mut. Dornburg 576, was genetically studied by crosses with the mother variety and characterized by seedling assays and investigations on development and yield formation. In comparison to the normal mother variety (Hordeum vulgare L., cv. Saale) mutant plants exhibit drastically reduced culm length, intensive tillering, a prolonged life cycle and a smaller biomass and grain yield formation. These characters are controlled by one gene in a pleiotropic way. The mutant responds with normal growth and development to the application of gibberellins.