this investigation was carried out during 2013 and 2014 rice growing seasons at the Experimental Farm of Agriculture Research Station, Sakha, Kafr El-Sheikh, Egypt, to study the magnitude of genotypic variation, the magnitude of both general and specific combining abilities (GCA & SCA) and their interaction with the two years as two different environmental conditions, estimation of the genetic parameters and broad and narrow senses heritability and the potentiality of heterosis expression for agronomic and yield and its components characters. Hybrids with a yield advantage of > 1.5t/ha over the highest yielding check variety Giza 178R were considered as promising. Among 12 hybrid combinations tested, six were most promising with mean performance of grain yield ranging from 11.62 t/ha for large stigma A/Giza 182R to 12.99 t/ha for G46A/Giza 178R. The yield over the best local inbred check, Giza 178 ranged from 1.10 to 2.47 ton ha-1. Among the four cytoplasmic male sterile (CMS) lines, G46A and IR 58025A were the best general combiners for grain yield. The restorer, Giza 178R was the best general combiner among testers for grain yield and most studied characters.