The contribution of the root-stock on the caffeine content of the coffee grains was studied in the Mundo Novo and Laurina cultivais of Coffea arabica and in the Rubosta cultivar of C. canephora which markedly differ in the alkaloid content. The results indicate that the root-stock, independently of its genotype, does not influence the caffeine content of the grains. Individual variation in caffeine content was found in the Robusta due to its genetic variability, pointing out to the possibility of selection for this characteristics in this material. It was also concluded that Robusta cultivars can be used as root-stock for Arabica selections without affecting the final product.