ABSTRACT- Barley (Hordeumvulgare L.) is one of the most important cereals in the world which is used as human and cattle feed and for malt production. One of the most important steps in a hybrid and selection breeding program of barley is the selection of suitable parents with high general (GCA) and specific combining ability (SCA) for grain yield. In order to estimate the combining ability and heterosis in barley for a number of qualitative traits, seven genotypes were crossed in one-way diallel crosses using Griffing (Method II). Grain number per spike, grain weight per spike, spike weight, ۱۰۰۰-grain weight, number of spikelet, plant height, spike length, peduncle length, days to physiological maturity, and spikelet density were measured. Results of variance analysis showed that there were very significant differences between genotypes for all the measured traits. General combining ability (GCA) effect was significant for all traits, ۱۶۶/۳۵۲ genotype had the highest value of GCA for grain number per spike (۴.۷۵۷), grain weight per spike (۰.۲۴۵), spike weight (۰.۳۷۸) traits, whereas Specific combining ability (SCA) effect was significant for all traits except for plant height, days to physiologic maturity, and spikelet density. Three crosses ۶۷/۱۱۰×۲۸۳/۳۵۲, ۹۵/۱۱۰×۲۱۶/۳۵۲ and Sahra×۲۱۶/۳۵۲ showed the highest values of SCA for grain number per spike (۷.۷۰۴), grain weight per spike (۰.۳۷۱) and ۱۰۰۰-grain weight (۸.۶۱۹), respectively. Moreover, dominance variance was the most effective factor in genetic control of traits. Three crosses ۲۱۶/۳۵۲×۲۸۳/۳۵۲, ۱۰۴/۱۱۰×۲۱۶/۳۵۲ and Sahra×۲۱۶/۳۵۲ showed the highest values of heterosis for grain number per spike (۴.۹۵), grain weight per spike (۴۴.۱۳) and ۱۰۰۰-grain weight (۳۱.۶), respectively. Maximum and minimum broad sense heritability was obtained in the number of grains per spike (۸۷/۷%) and spike density (۴۷/۳۶%) respectively. Lowest and highest narrow sense heritability was obtained for peduncle length (۱۵/۷۲%) and weight of grains per spike (۵۰/۵%), respectively. Estimates of SCA showed that ۹۵/۱۱۰×۲۱۶/۳۵۲, such as ۶۷/۱۱۰×۲۸۳/۳۵۲ crosses could be used in breeding programs to release cultivar to increase yield-related traits.