An experiment was carried out in laboratory to evaluate the effect of water stress seeds germination and vigor. Seeds of UFV-9 (Sucupira) variety were placed to germinate in germitest paper soaked with solutions of sodium chloride (NaCl), mannitol and polyethylene glycol (PEG 6000), using five osmotic potentials: 0; -0,1; -0,3; -0,6 e -0,9 MPa. Standard germination and vigour as first count, seedling lenght, dry matter production of seedlings and hypocotyl/radicle relation were evaluated. The results showed that negative osmotic potentials induced great reduction of soybean seeds germination and vigour. The vigour was more affected than seed germination with the increase of osmotic solutions concentration. Osmotic potentials lower than -0,3 MPa were critical to seed germination and vigour. The polyethylene glycol (PEG 6000) had an adverse effect on the characteristics evaluated.