The purpose of this study was verify the biochemical changes associated with the osmoconditioning of soybean seeds from the varieties UFV 10 (Uberaba), IAC 8, Doko RC and Savana. The biochemical evaluations were performed during the controlled imbibition treatments. Seeds were either osmoconditioned at 20°C, during four days, in a -0.8MPa polyethylene glycol (PEG 6000) solution or imbibed in water for the following periods: zero, 6, 12, 24, 48 and 96 hours. Protein and lipid contents and the protein/lipid relation at the different imbibitional times were determined. The relative ratio of saturated and unsaturated fatty acids and the soybean seed germination and seedling emergence were evaluated after imbibition of the seeds. Soybean varieties had great variability on seed chemical composition. The osmoconditioning was effective in avoiding lipid reduction during the imbibitional time and also in increasing seed germination and emergence percentage, while promoted smaller reduction in the unsaturated fatty acid content. A significant increasing in protein content, during imbibition, was observed.