Evaluating of seed viability by Lab. germination and Tetrazolium tests were a valuable approach to predict the number of emerging and survivingplants in the field. The present investigation aimed to determine the value of lab. Germination as prerequisite requirement to sale or purchase the seed in the market from one hand, and determine the value of electrical conductivityand tetrazolium as a quick and suitable lab. tests to predict the performance of soybean seeds under field conditions from the other hand. Lab. tests were conducted at Seed Technology Research Department, Agricultural Research Center, Giza, according to the international rules, while field trails were undertaken at Sakha Research Station (widely adapted for Egyptian Regions) during 2008 and 2009 growing seasons. The results showed highly significant correlation between the numbers of seeds capable of producing normal seedlings under lab. Conditions (germination percentage) and those emerged and surviving plants in the field (field emergence and survival percentages) indicating the important of sowing seeds of high germination capacity to achieve a good field establishment. The correlation coefficient for the relationship between the number of stained seed due to TZ treatment and those resulted in the field was also significant, indicating that the TZ test can provide more quick evaluation of soybean seed quality and be considered at calculating seeding rate. The value of electrical conductivity to predict seed performance in the field cannot be emphasized.