Two field experiments were carried out during the two successive growing seasons (2006/2007 and 2007/2008) at El.-hammam farm, Mersa Matrouh, Northern West Coast (NWC) of Egypt. This work was aimed to study the effect of supplementary irrigation treatments (rainfall, one and two supplementary irrigations) and mixture of seeding rates between barley and short life berseem, fahl var., (100% barley, 75% barley+25% berseem, 50% barley+50% berseem, 25% barley+75% berseem and 100% berseem), on fresh, dry forage yields and its components as will as water use efficiency (WUE). The summarized results indicated that the highest value of fresh and dry yields (Ton/fed.) through the tow growing seasons were obtained from the two supplementary irrigations treatment. The mixture of seeding rates of 25% barley plus75% berseem produced the maximum values of fresh and dry forage yields. Two supplementary irrigations for the seeding rates mixture of 25% barley +75% berseem treatment gave the highest value of fresh and dry forage yields. However, WUE was recorded its maximum value from the interaction between rainfall and seeding rates mixture of 25% barley plus 75% be seem treatment in the two growing seasons. The reverse was true with the interaction between two supplementary irrigations and the same mixture of seeding rate (25% barley + 75% berssem) in the two growing seasons.