Soybean grains were stored extreme condition, high temperature (40℃) and high relative humidity (> 95%), for 7 weeks. The extreme storage condition accelerated deterioration of seed viability based on germination percentage and seedling growth. Seed germination percentage was continuously decreased as the storage period increased. The percentage was dramatically reduced at 4th week. During the deterioration of seed, seed chemical properties were also changed. Sugars content, however, showed no large changes in content. The most conspicuous change was observed in electric conductivity by seed leachate. EC changes precisely reflect the seed viability change during storage. Although lipid peroxidation measured by TBA test was increased as storage period increased, the peroxidation did not show great change as much as EC change. Water activity of seeds was dramatically decreased until 2 week after storage then the activity was stable until 5 weeks after storage at which microbial contamination occurred. Isoflavone content was decrease at 3rd week, the content was reduced by 18 % at 7th week as compared to control. Proteome analysis revealed that there was several changes in polypeptide profile in imbibed axis during storage under unfavorable conditions.