. "Guaraná" seeds (Paullinia cupana var. sorbilis (Mart.) Ducke) were classífied in classes of size by perforated screens of 7,94mm, 8,73mm, 9,53mm, 10,32mm, 11,11mm, 11,91mm, 12,70mm, 13,49mm and 14,29mm of diameter round holes. in order to determine a standard size for the production of seedlings. The seeds were sown 2cm deep, in substratum of tanned sawdust treated with methyl bromide. Atthe end of 150 days after sowing, in two years of experimentation, data was taken on theemergence percentage and speed of emergence. Seed retained on 13,49mm, 14,29mm,10,32mm and 11,91nun size screens had average emergence higher than 80%. The dataon emergence speed showed that the larger seeds had superior index mean than the smaller ones.