A field experiment was conducted at the Institute of Agriculture – Karnobat, Southeastern Bulgaria in three growing seasons. Ten advanced lines developed by experimental mutagenesis along with parent line and standard varieties Obsor and Emon were laid out in a complete block design with 4 replications. Variability and heritability for yield-related traits and grain yield were studied. There were significant differences among advanced lines for all studied traits. Heritability in broad sense ranged from 48.51 % for grain weight per spike to 79.36 % for spike length. The grain yield of advanced lines was significantly higher compared to the parent and varied from 5.34 t/ha in M5/14 to 6.28 t/ha in M5/14. Moreover, lines M5/1, M5/3, M5/10, and M5/19 had higher grain yield than the high-yielding standard variety Emon. Hence, using these lines in the breeding program of winter barley could lead to the improvement of grain yield.