A study was conducted during the period of three concessive years from 2016/2017 to 2018/2019 in the experimental field of the Institute of Agriculture - Karnobat, Southeastern Bulgaria with the aim to investigate the variability, heritability, and correlation between grain yield and yield-related traits of breeding lines of facultative barley under rainfed conditions and to select lines with desirable agronomic traits for including in further breeding work for the development of facultative barley varieties for Bulgarian environments. The traits: number of days to heading, plant height, spike length, spikelet number per spike, grain number per spike, grain weight per spike, and grain yield were recorded. The analysis of variance indicated significant differences between 6-rowed facultative barley genotypes in the studied traits. Most of the traits under the study showed the relatively low phenotypic and genotypic coefficient of variation. The estimates for heritability in broad-sense were high for the number of days to heading, grain weight per spike, and 1000-grain weight and very high for plant height and spike length suggesting a possibility for improvement of those traits through selection based on phenotype. Whereas low heritability of grain yield was found indicating that the phenotypic selection could be ineffective under these specific conditions. Grain yield of facultative barley accessions showed a significant positive correlation with spike length, spikelet number per spike, grain number per spike and grain weight per spike. The traits with the highest positive direct effect on grain yield were grain number per spike and 1000-grain weight while days to heading had a highly negative direct effect on grain yield. A combination of high heritability and high direct on grain yield in 1000-grain weight and days to heading shows that those traits may be used in early-generation selection in breeding of high-yielding facultative lines. The accession TX01D236 had a significantly higher grain yield compared to check varieties and could be included in future breeding work.