Studies of heterosis and combining ability  of six photo /thermo-sensitive testers were estimated using line x tester analysis for some agronomic characters and yield and its components to get useful information for two-line system in hybrid rice breeding in Egypt . The outstanding hybrid combinations for grain yield plant^-1 were PTGMS-5/Dular (45.26%) with significant standard heterosis for ,panicle length (28.22%) productive tillers plant^-1 (24.19%) ,panicle weight (26.93%) ,filled grains panicle^-1 (25.89%),spikelets panicle^-1(14.19%) ,spikelet fertility % (10.20% ) and 100-grain weight (35.62% ) .In the mean time ,PTGMS-14/Norin PL9,PTGM-7/Dular ,PTGMS-14/Giza178 and PTGMS-5/Giza 178 were considered as promising hybrids. Among the six PTGMS lines,PTGMS-5  and PTGMS-14  were the best general combiners for grain yield and all studies characters.The testers , Dular , Giza178,M202 and Pecos were the best general combiners among testers for grain yield and most studies characters.