Eight rice cultivars (Oryza sativa L.) having diverse morphological and agronomical character were crossed in all possible combinations (excluding reciprocals) to determine nature of gene action and inheri‌tance of some quantative characters in Fl and F2 generations. Date were collected on days to heading, plant height, panicle length, number of panicles per plant, spikelet sterility, numberof spikeiets per panicle, bi‌ological yield per plant, grain yield per plant, harvest index, 1000 grain weight, grain length and grain width. The results of variance analysis of diallel tables (Hayman 1954a, and Jones, 1965) indicated that the addi‌tive genetic variance (a) was significant and larger than non-additive (B) for all characters except grain yield per plant in both generations. Additive (D) as well as dominance estimates (H1) and (H2) were significant for nine characters, whereas only the non-additive component was significant for biological yield per plant, grain yield per plant and har‌vest index. Mean degree of dominance (F11/D)1/2 was less tthan unity (<1) indicating partial dominance for plantial dominance for plant height, but panicle length, spikelet sterility, 1000 grain weight and grain length in both Fl and F2 generations, but it was equal or near unity suggesting complete dominance for days to heading. However, it was greater than unity (>1) indicating over-dominance for the number of panicles per plant, the number of spikelets per panicle, biological yield per plant, grain yield per plant, harvest index, and grain width in both generations. The significance levels of the parameters estimated in Fl and F2 generally were in agreement. In this case, the results obtained applying one of these biometrical analysis methods, either in Fl or in F2 generation, May be used in Making decisions concerning the type of breeding system and in selecting breeding material. Estimates of narrow sense heritability were high for days to head‌ing, plant height, panicle length, spikelet weight and grain length in F2 generation. Moderate heritability estimates were observed for the num‌ber of spikelets per panicle and low for the number of panicles per plant, biological yield per plant, grain yield per plant, harvest index, and grain width in both generations.