ABSTRACT: In the present study, we aimed to assess the in vitro viability of pollen grains from maize cultivars collected at different times and days in the field. Four cultivars (Sol da Manhã, XB 6012, XB 8010, and BRS 2020) were evaluated from the second to fifth day of anthesis in three times. Pollen samples were evaluated for their in vitro viability through standard germination test in liquid and solid media and tetrazolium staining. The experimental design was completely randomized, in 4x4x3 split-split plots with four replicates. Data were subjected to analysis of variance followed by a means clustering test and linear regression analysis. The average percentage of viable pollen varied according to the day, collection time, and cultivar. In general, XB 8010 and BRS 2020 had the highest frequency of viable pollen. The highest percentages of viable pollen were observed on the second day of anthesis at 10:00h.