An experiment was carried out under field conditions, on a soil classified as Ultisol (?Terra Roxa Estruturada?), in order to study the effects of different types of soil preparation on corn seed characteristics: minimum tillage, conventional preparation (plowing and two disking), and revolving hoe with three rotor speeds (121.50, 171.53, and 216.00rpm) and two heights of the rear shield (completely up and completely down). The seeds were classified by oblong sieve holes (16 x 3/4?, and 14 x 3/4?), and circular sieve holes (24, 22, 20, 18 and 16), for determining the retained percentage, and 100 seed weight. The minimum tilage treatment revealed a tendency to show smaller seed sizes and smaller weight in relation to conventional preparation. Soil preparation with revolving hoe produced seed sizes and weight similar to those obtained from the conventional method of soil preparation, which showed smaller percentage of germination, but were similar to the other types of preparation concerning to seed vigor.