The present work aimed to investigate the effect of harvest time and site of fruit picking within the plant on the physiological quality of cotton seeds. In laboratory, seeds were submitted to the tests of viability: standard germination and tetrazolium, tests of vigour (water submersion, tetrazolium and emergency rate in field). The results of seed viability tests showed no statistical differences in the treatments harvest time and picking site of fruit. The results of the water submersion and emergency rate tests, showed significant differences for the treatments harvest time and site of fruit picking. The highest levels of seed vigour were obtained when the harvest was made 2 weeks after 50% of fruits open.