A study was carried out in laboratory and greenhouse conditions to investigate the osmoconditioning effect on soybean seed vigor and germination of the varieties UFV 10 (Uberaba), IAC 8, Doko RC and Savana. The osmoconditioning was conducted by placing the seeds in contact with a -0.8MPa polyethylene glycol (PEG 6000) at 20°C during four days. Two controls were used: untreated seeds and water soaked seeds, at the same temperature, until they reach the same moisture content of the osmoconditioned seeds. The seeds were evaluated by the standard germination test (first and final count), germination under water stress, seedling length and dry matter weight. The seedlings percentage of emergence and the speed of emergence-index were determined in sand seedbed. The results showed that PEG 6000 solution limited both seed imbibition and final moisture content. The osmoconditioning was efficient in increasing seed performance, under adverse conditions. The water imbibition decreased soybean seed germination, vigor and seedling emergence. The soybean varieties showed different performance in relation to seed vigor, at different imbibition treatments.