The main purpose of this work was to evaluate, through germination tests, the importance of the weight on rice seeds (Orza sativa L.). Batatais, Pratão Precoce. IAC-120, IAC-435 and IAC-1246 varieties were tested. The trial was conducted in the Seed Laboratory of the "Departamento de Agricultura e Horticultura da Escola Superior de Aricultura Luiz de Queiroz", from November, 1973. to December, 1974. Seeds of each variety was submited to a controled ventilation action through a blower, allowing the separation of each variety in to three fractions, with different weights, that is, light, median and heavy. The light, median and heavy seeds obtained were stored indry chamber and in laboratory. The germination tost were done in three periods (March/April, July and December, 1974), using as experimental design a factorial 3x2 whose variables were three weights and two environments of seeds conservation with four replications. Data analyses and the interpretation of the obtained results allowed us to draw the following conclusions: a) the heavy seeds and the median weight ones presented a higher percentage of germination than the light seeds in all studied varieties; b) this effect was less intense in the case of the Batatais and IAC-1246 varieties; c) the dry chamber environment showed superior to the laboratory for he conservation of the seeds.