Although the rootstock plays a fundamental influence on the behaviour of the fruit tree and on the possibilities of fruit growing in any soil and climate orchard condition, this trial has shown that the cultivar has a similar or greater effect than the rootstock on the behaviour of the fruit tree in such interesting aspects as vigour, early bearing and cumulative production of each rootstock-scion combination, all of them key factors to establish the orchard design more adequate to the particular growing conditions of each place. The behaviour of four sweet cherry cultivars (Marvin, Burlat, Summit and Sunburst) on the rootstocks Saint Lucia 64, Masto de Montañana, and MaxMa-14 has shown the best performance of the Saint Lucia 64 for the tree aspects of vigour, early bearing and cumulative production in relation to the other two rootstocks.