The mutant line carrying many mutated characters was induced after mutagenic treatment of seeds of spring wheat variety 'Rena' with N-ethyl-N-nitroso urea (2, 4, 6 mM). This mutant line was named 'KS-5'. The most characteristic change in this mutant line is the decrease in the number of days to maturity when compared with 'Rena'. The mutant line is ready for harvest at the same time as variety 'Kosutkz', which is the earliest, of all the former Czechoslovak varieties. The mutant line 'KS-5' is shorter by 10 cm (average length of the stem is about 65 cm) than the parent variety 'Rena' and also more resistent to wheat powdery mildew.