Two  pot  experiments were performed at the Experimental Station Farm , Faculty of Agriculture Mansoura university during two successive summer seasons of 2007 and 2008. This work was conducted to study the role of some antioxidant materials in alleviation the harmful effect of different salinity stress levels on sweet pepper cv. California wonder. Data show that high salinity stress levels decreased all growth parameters as well as fruit yield of pepper plant  during the two growing seasons (2007/2008). 6000 mg/l salinity stress level was the most effective in this respect.                 On the other hand, the data show that antioxidant materials such as HA (1000 mg/l), Salicylic acid (250 mg/l), Ascorbic acid (250 mg/l),  Put.( 1 mg/l) used as presoaking and foliar spray gave positive effect on growth parameters and yield of pepper plant . It could be show that applied antioxidant materials (ASA and SWE) were the most effective in increasing growth parameters of pepper plant  during the two growing seasons. According to the effect of the interaction treatments of salinity stress levels (2000, 4000 or 6000 mg/l) with each of antioxidant treatment presoaking + foliar spray (HA, SA, ASA, Putrescince and SWE ). It could be show  that any of applied antioxidants increased all growth parameters under low salinity level (2000 mg/l). In this case, the applied antioxidants completely mitigated the harmful effect of 2000 mg/l salinity level on growth of pepper plant. It could be say that the applied antioxidants completely counteracted the harmful effect of low and moderate salinity levels (2000 and 4000 mg/l) and partially counteracted the harmful effect of salinity stress level (6000 mg/l) on pepper yield. Ascorbic and SWE were most effective in this respect.