In the years 1996-1997 development and yields of oats grown in mixtures with barley and in pure sowing were compared. Six nitrogen doses were applied: 0, 50 kg (50+0+0), 65 kg (50+15+0), 65 kg (0+35+30), 80 kg (50+30+0) and 95 kg (50+15+30) before sowing, at shooting and at heading, respectively. In 1996 with unfavourable weather conditions, oats in mixtures developed greater number of stalks and seeds and yielded relatively better than in pure sowing. In 1997 barley developed well in mixtures, while oats worse than in pure sowing. Total yields of the mixtures were proportionally higher than oats and barley yields in pure sowing. Reaction of oats in mixtures to N fertilisation was similar as in pure sowing. To obtain high yields the dose of 65 kg N was sufficient, but in 1996 the best results produced late fertilisation (0+35+30), while in 1997 the 50+15+0 system.