Annual grass (Lolium multiflorum) is a grass species in the genus Lolium belonging to the Poaceae family. In recent years, annual grass, which adapts well to the climate and soil conditions in Turkey, has been used as a good alternative forage source to close the forage deficit. Seed bio-priming applications with plant growth promoting rhizobacteria (PGPR) are widely used because they improve germination and seedling development. Therefore, the aim of this study was to investigate the effects of bio-priming applications with different bacterial lines on germination and seedling development of Italian ryegrass seeds. Elif Italian ryegrass variety registered by Aegean Agricultural Research Institute was used in the study. In the study, 9 different Bacillus species bacterial lines with 108 cfu/microorganism density were used for bio-priming application. Successful germination and seedling development are very important for obtaining high yield. As a result of the study, no significant difference was obtained between the treatments in germination percentage, but it was determined that SY2 and SY5 (Bacillus sp. isolate) showed superior performance compared to the control in terms of shoot length and shoot wet and dry weights.