Photosynthetic characteristics of seedling leaves and mesophyll protoplasts in Lolium species were assessed to search possibility for improvement of two cultivated species, L. pereme and L. mulíiflorum. Smáli size of mesophyll protoplasts was a suitable trait for estimating photosynthetic characteristics, when combined with high photosynthetic rate (Fn) P^r protoplast. L. rigidum and L. suhlatum háve more potential for improvement of because of higher per unit leaf aiea and per chlorophyll (Chl) and higher rate of Chl content: surface area of protoplast, than L. pereme and L. multiflorum.