Soybean, seeds (Glucine max (L.) Merrill) of IAC-Foscarin 31'(Group Vl)and ' IAC-8' (Group VIII) were harvested we ekly in field plots planted in 1981, 1982 and 1983; after harvests, seeds were stored under normal environment conditions, dry chamber (35% RH) and cold chamber (10°C + 80% RH) during six months at the Seed Laboratory of the Escola Superior de Agricultura "Luiz de Queiroz", Universidade de Sio Paulo,Brasil. The behavior of seeds during storage was evaluated bimonthly by germination, accelerated aging, electrical conductivity and seedling emergence tests; plant performance was studied in field experiments planted in 1982, 1983 and 1984. Results showed that all laboratory tests were related to field emergence, but electrical conductivity was found to be the most efficient test to characterize physiological quality and field emergence potential. Seeds of'IAC -8' showed better quality than 'IAC-Foscarin 31', but this fact was related to environmental conditions during maturation and harvest time. Storability was determined by environmental relative humidity and initial quality of seeds.