The successful establishment of crop mainly depends on good quality seed which germinate rapidly, uniformly and able to withstand under environmental adversity after sowing. Laboratory experiment was conducted at Seed Technology Unit, Mansoura, Egypt to evaluate the effect of rice seed priming (c.v. Giza 177) with CaCl₂ at osmotic potentials (- 0.75, -1.00 , -1.25 , -1.50  MPa and distilled water) for 6 , 12, 24 , 36 and 48 hours on seed germination, seed and seedling vigor under normal and salinity stress. The obtainedresults of this study indicated that salinity levels (9 dS/m) delayed germination, seed and seedling vigor characters compared with normal salinity (0.3 dS/m). Rice seed priming with CaCl₂ at (-1.00 MPa)  followed by (-1.25 MPa)  gave the highest values of germination percentage, speed of germination index, germination rate, germination co-efficient, germination energy %,seedlings length, seedlings dry weight, water uptake % and decreasing mean germination time as well as time to 50 % germination compared with control (distilled water) under salinity stress. Whereas, priming seed with distilled water (control) resulted in the lowest germination characters under salinity stress. Priming duration 24 h showed its superiority in improving germination characters comparing with other priming durations. It could be concluded that, priming rice seed (c.v. Giza 177) with osmotic potential (-1.00 MPa) for 24 h can reduce the injurious effects of salinity stress.