The present work was carried out at the Federal University of Viçosa, in the growing season of 1990/91, to evaluate the physiological quality of hard seeded soybean by using fast tests. The cultivars Doko, Savana, UFV-1 and UFV-10 (Uberaba), with permeable seed coat, and IAC-14 and lines IAC 80-3110, TG x 849-9D and TG x 849-41D, with seed coat impermeability, were submitted to four harvest times: at R8 stage and 15, 30 and 45 days after this stage. The following evaluations were carried out in laboratory to determine the physiological quality of the seeds: tetrazolium, pH of the exudate and electrical conductivity tests. The standard germination test was used as a control test. The lines TGx849-9D and TGx849-41D, and the cultivar Doko, had the best seed quality, while the cultivar Savana and line IAC 80- 3110 had less tolerance to seed deterioration. Seed coat impermeability was not the only factor responsible for the physiological quality of the seed. The delayed harvest of 30 and 45 days induced the seed deterioration in all the studied genotypes. The Tetrazolium was the most efficient fast test, while the electrical conductivity test varied according with the evaluated genotype. The pH of the exudate test may be used to produce quick information about the physiological seed quality.