This study was conducted to evaluate the effects of mandatory selfing on morphological and agronomic traits of Orchard grass and smooth bromegrass in 2013-2014. For this purpose, 25 genotype of two grass species were established during 2010-2012. In 2013 four plants were randomly selected from each genotype, and half of the panicles of each genotype were bagged for obligate selfing and the others were allowed to open pollination. Therefore three populations including self progenies (S1), open pollinated (OP) progenies and parental genotypes (S0) were developed as the genetic material of this study. Three populations were evaluated using a split plot experiment according to randomized complete block design with four replications in 2013. For each species S1, OP and S0 were considered as main plots and 25 genotypes as sub plots. Results indicated that there was high phenotypic variation among the genotypes of each population in two species of orchard grass and smooth bromegrass for most of the traits. In orchard grass results showed that selfing significantly decreased dry mater yield of cut1 and cut2 (44 and 20 percent, respectively) from parents. Also OP population had significant difference compared to parental population for this trait. In smooth bromegrass, there was no significant difference between S1 and parental population for most of the traits. In this species, flowering of S1 was occurred sooner than parental population. However, S1 population had significant decrease in plant height compared to parental population. The highest genetic variance was observed for fresh matter yield in OP and S1 populations of two studied species. Genetic and environmental variance for most of traits in S1 was more than OP in both species. Heritability of dry mater yield in orchard grass was estimated 6 % (broad sense heritability) and 22 % (narrow sense heritability) based on variance components method and 17 and 28 % (narrow sense heritability) based on parent-offspring regression in selfing and open pollination progenies, respectively. Heritability of dry mater yield in smooth bromegrass was estimated 14.7 % (broad sense heritability) and 33 % (narrow sense heritability) based on variance components method and 3 and 28 % based on parent-offspring regression in selffing and open pollination progenies, respectively. Based on open pollination progeny test, genotypes 9, 5, 24, 6 in orchard grass and genotypes 6, 1, 20 in smooth bromegrass showed higher general combining ability for dry mater yield. Results showed that self and open pollination progeny tests probably have the enough efficiency for parent selection in two species. The results also showed that the production of the pure lines in orchard grass and smooth bromegrass is possible in order to develop new improved varieties and to construct future genetic studies. Key words : self fertility, open pollination, heritibility, progeny test, orchard grass, smooth bromegrass