DS2 and control. Leaf dying score (LDS) Guinea grass and Napier grass have not significant effect of drought stress treatment. Treatment DS2, DS25 and DS258 have not significant difference with control on Guinea and Napier grasses. Relative water loss ratio affect by treatment of drought stress. Relative water loss ratio showed significant difference with control on Guinea and Napier grasses. Stress period DS2 to DS258 significant increased RWLR on Guinea and Napier grasses. Drought tolerance on stress period DS258 significant decreased on Guinea grass but have not significant on Napier grass. Water use efficiency has been defined as the ratio of economic yield to total water use or transpiration (Johnson and Henderson, 2002). Water use efficiency (WUE) was volume of water consumed by grass for 60 days after uniformity cut. Three times stress period (DS258) have decreased WUE of Guinea grass compared to DS25, DS2 and control. Napier grass have water use efficiency did not effect by drought stress period, there were not significant difference between DS258 with DS25, DS2 and control