The alleviation effects  of  ascorbic  (AsA) and  salicylic (SA)  acids  as well as  seaweed  (SWE) and  yeast (YE)  extracts  against  salinity stress  on soybean plant were evaluated. Two experiments were conducted at the greenhouse and labs. of the Agric. Bot. Dept., Fac. of Agric., Mansoura Univ., and Seed Technology Research Unit,  Field Crops Research Institute,  Agric. Research Center, during the two growing Seasons 2010 and 2011. Salt stress was imposed by dissolving natural salt crust in tap water to obtain saline irrigation water at 5000,6000,7000,8000 and 9000 mgL^-1. Results indicated that all tested substances partially restored the salinity induced decrease in seed yield, with AsA and YE were the most effective in this respect. Total phenols, proline and endogenous ascorbic acid contents were increased in response to either salinity stress , stress alleviators or their interaction. The ratio between Na and K in both shoots and roots was decreased in response to stress alleviators. In addition, seed oil and protein contents were increased in salt–stressed , stress alleviators- treated plants compared with salt-stressed only plants. In addition, results indicated that the alleviative effect of the applied stress mitigators was evident not only on salt-stressed plants but also on their descendant seeds where their germination, vigour, and seedling establishment were enhanced. It is concluded that AsA, SA, SWE and YE, preferably the first and the latter, could be used to maintain yield of soybean growing in salt-affected soils.