The objective of this research was to study the genetic behavior of some vegetative, yield and yield component traits at some indica and indica-japonica rice (Oryza sativa L.) genotypes and their hybrids in Egypt. Half diallel experiment was conducted to evaluate the performance of 15 F₁ rice hybrids along with their six parents i.e., Giza 178, GZ 6296, PR 78, GZ 9057, G 46B and Large stigma B at Sakha Agricultural Research Station Experimental Farm and Rice Research and Training Center (RRTC), Sakha, Kafr El-Sheikh, Egypt during 2014 and 2015 summer seasons. Analysis of variance revealed highly significant differences among genotypes, parents and crosses for days to heading, plant height, panicle length, panicles plant^-1, panicle weight, 1000-grain weight, spikelets fertility % and grain yield plant^-1. Both general (GCA) and specific (SCA) combining ability variances were found to be highly significant for all characteristics. The ratio of ó² gca / ó² sca was less than unity for all studied characteristics except for days to heading, indicating the preponderance of non-additive

genetic variance in the inheritance of these characteristics. High broad sense heritability estimates observed for all studied characteristics which suggest high component of heritable portion of variance, which is the portion exploited by breeder and that selection for these traits can be achieved directly based on their phenotypic performance. While, heritability estimates in narrow sense were relatively low for the same traits. According to the mean performance for studied characteristics, cluster analysis divided the six rice genotypes into two major branches.