This experiment was conducted to evaluate the effects of NaCl priming with KNO3 on the germination traits and seedling growth of four Helianthus annuus L. cultivars under salinity conditions. Seeds of four spring sunflower (Armawireski, Airfloure, Alestar and Ismailli) were primed with KNO3 (-1.0 M Pa) for 24 h in continuous 30 degrees C. Primed (P) and un-primed (NP) seeds were cultured in medium grade perlite and placed in greenhouse for 40 days. Experiments were conducted using various osmotic pressures induced by NaCl (5, 10, 15, 20 and 25 dS m(-1)) in salinity experiment. Results showed that germination percentage of primed seeds was greater than that of un-primed seeds. Radicle length, seedling height and dry weight and leaf number of plants derived from primed seeds were higher compared with un-primed seeds. Na content of plants derived from primed seeds was higher than that of un-primed ones. In contrast, K content of priming resulted plantlets was comparatively higher compared with un-primed counterparts. It seems that salinity tolerance in priming resulted plantlets was due to higher potential of these plants for osmosis regulation. Decreasing osmotic potential progressively decreased both root and shoot length.