Iran is located in a hot and dry region. As a result of low precipitation and a vast area of salty and alkali soil, osmotic pressure is very high in most parts of the country (i.e., osmotic potential is more negative). In the present study four levels of osmotic pressure (-0.25, -0.35, -0.45, -0.50 MPa) were created artificially, by polyethylene glycol (PEG) and treatment of three seed types, namely, barley, corn and canola. The study aimed at finding the seeds with better germination potential under high osmotic pressure. The seeds' germination potential under different levels of osmotic pressure was also investigated. The experiment was conducted with four replications at the Laboratory of Faculty of Agriculture, Islamic Azad University, Saveh Branch, in a completely randomized design. Parameters under study were germination rate and germination percentage. Results showed that germination rate was not affected by osmotic potential. Considering germination percentage, only osmotic potential of -0.50 reduced germination percentages of corn seeds. Levels of osmotic potential did not affect seed germination in barley and canola.