Malt barley and durum production continues to increase in eastern Montana. These crops are produced under sprinkler and flood irrigation as well as dryland conditions. Previous research indicated that some crops respond differently under sprinkler and flood irrigation. This study evaluated effect of seeding rate on yield and quality of malt barley and durum when grown under dryland fallow conditions, sprinkler irrigation, and flood irrigation. Dryland seeding rates were 1.85 x 10⁶, 2.47 x 10⁶, 3.09 x 10⁶, and 3.70 x 10⁶ pure live seed/ha. Seeding rates under irrigation were 2.47 x 10⁶, 3.09 x 10⁶, 3.70 x 10⁶, and 4.94 x 10⁶ pure live seed/ha. Fertilizer, pesticides, and irrigation water were applied as necessary. Under dryland fallow conditions, malt barley yielded most with a seeding rate of 3.09 x 10⁶ seed/ha. Seeding rate did not significantly affect percent plump seed or grain protein. Under both sprinkler and flood irrigation, malt barley yielded most at a seeding rate of 3.70 x 10⁶ seed/ha. Percent plump seed and grain protein were not affected by seeding rate under sprinkler irrigation, but increased seeding rate under flood irrigation resulted in reduced percent plump seed. Under dryland fallow conditions, durum yield, test weight, grain protein and hard vitreous amber color were not affected by seeding rate. Under sprinkler irrigation, seeding rate did not affect durum yield, but hard vitreous amber color and grain protein were reduced by increased seeding rate. Under flood irrigation, durum achieved the highest yield with a seeding rate of 3.70 x 10⁶ seed/ha, while grain protein, hard vitreous amber color and test weight were not affected by seeding rate. Both malt barley and durum grain protein were greater under sprinkler irrigation than under flood irrigation.