Combining ability and heterosis studies were performed on half diallel mating. The basic material for the present study consisted of six diverse genotypes of oats viz: Alguda,  Anatolia, Kangaroo, ICARDA tall, Bihuth and Shifa'.15 F₁ hybrids and their parents were grown in randomized complete block design with three replications. Observations were recorded on six quantitative traits. The analysis of variance revealed significant differences among the parents and their crosses for all the studied traits. The estimates of variance due to non-additive gene action (σ²D) was much higher than the corresponding additive genetic variance (σ²A) for all the traits under evaluation.Values of GCA effects revealed that ICARDA tall was found to be the best general combiner for biological yield amongst all the parents. It was also found to have significant positive GCA values for other traits. On the basis of significant SCA effects, hybrids ICARDA tall x Bihuth and Alguda x Bihuth recorded highest SCA effects for biological yield, also showed positive and significant SCA values for other traits. The F₁ hybrids were showed the best specific combinations viz; Bihuth x shifa' for days to 50% heading and days to 75% maturity, Anatolia x Kangaroo for plant height at maturity,Anatolia x Bihuth for numbers of tillers. Highest significant and positive heterosis for biological yield was shown by F₁ hybrid Alguda x Bihuth followed by ICARDA tall x Bihuth. These crosses combinations also exhibited highly values with positive and significant heterobeltiosis for two traits viz; plant height at maturity and growth rate.