A study was conducted to assess the magnitude of heterosis for grain yield and its components over mid parent (MP), Better parent (BP) and standard heterosis (SH) in rice hybrids (Oryza sativa L.) through line x tester analysis. The present study comprised of three lines and ten testers. The resultant thirty hybrids along with their thirteen parents were evaluated during 2009 to 2010 in a randomized block design with three replications at Plant Breeding Farm, Department of Genetics and Plant Breeding, Annamalai University, Chidambaram. The analysis of variance indicated significant amount of variability among the genotypes for all the seven traits studied. The cross combinations IR 58025A x ASD 19, IR 62829A x ASD 16, PUSA 3A x IR 42 were found to be promising for seed yield as they had high percentage of standard heterosis.