The present study was developed at the seeds research Lab of the Phytotechny Department at Federal University of Viçosa, MG, Brazil. The objective was to propose the utilization of the tetrazolium test as a complementary test to the standard germination test, for the evaluation of germination and the vigor of cotton seeds. The treatments were constituded of eight lintered seed plots, having differents percentage values of germination (Plot 1 = 30%, Plot 2 = 40%, Plot 3 = 45%, Plot 4 = 55%, PIot 5 = 65%, Plot 6 = 75%, Plot 7 = 85% and Plot 8 = 90%). The germination standard test, the tetrazolium test and the seedling emergence in sand were applied to seeds from the different treatments. The seeds of the emergency test in sand were treated with Captafol plus Quintozene. The results showed that: a) the evaluation of the germination percentage according to standard germination test was sensibly harmed by the presence of fungus in the seeds; b) a high correlation coefficient between the tetrazolium and the the standard test was observed (r = 0,87). However a higher correlation coefficient (r = 0,90) was obtained between the tetrazolium test and the emergency test in sand because the treated seeds did not suffer fungus effects; e) at germination standard test of lintered cotton seeds, the presence of fungus at radicle and hypocotyl turned dificult the evaluation and the interpretation of the germinative potential. Under this circunstances the tetrazolium showed itself useful as a complementary test.