This work was carried out to determine the effect of a plant growth stimulant on the fruiting of tomato plant, Lycopersicon esculentum Mill. cv. Miguel Pereira. In this trial, Atonik (biostimulant composed of sodium mono-nitroguaiacol and other nitrogenated aromatic compounds) at 0.5 ml/l concentration was sprayed once just before flowering; once in the anthesis of the first two flowers of first cluster; three times, one in the anthesis of the first two flowers of first cluster and twice more at a 7 day interval; and three times, one when the first fruit from the first cluster was developed and twice more at a 7 day interval. It was verified that Atonik applied when the first fruit of the first cluster was developed, and twice more at 7 day intervals, increased the number of fruits of the tomato plant; Atonik applied during anthesis of the first two flowers of the first cluster damaged the classification of the fruits and increased the number of aborted flowers of the tomato plants.