Eight lactating Holstein cows in a duplicated 4×4 Latin-square experiment were used to compare the effect of differently processed barley. Treatments were: 1. ground barley, 2. steamrolled barley, 3. dry-rolled barley (PI=72%), 4. dry-rolled barley (PI=81%). Treatment 2 and 3 compared to 4 showed higher milk (28.25, 28.82 vs 26.59 kg/d), and protein (0.84, 0.86 vs 0.80 kg/d) and treatment 1 and 3 showed higher 4% FCM (27.42, 27.44 vs 25.57 kg/d), compared with treatment 4. These results indicate diets consisting of 25% ground barley can be used effectively, without any negative effects on performance.