Flower or fruitlet thinning is one of the cultural practices used for improving the fruit quality and regulation of yield. The effect of ATS (FloreduX), 6-BA (MaxCel) and metamitron (Brevis) on yield and some fruit characteristics of apple trees cv. Šampion/ M.9 T337 was evaluated. Chemical thinning agents were applied alone, as subsequent spraying or as a tank mixture. Due to the possibility of damage to flowers by the announced frosts, a preparation containing sea algae – Goëmar was added in some treatments. Thinning with only MaxCel resulted in an excessive reduction of the total yield expressed in the number of fruits and their mass, but using MaxCel after flower thinning with Floredux gave very good results. The total yield expressed in kg tree^-1 was even bigger than in the control, but the share of fruits with diameter above 7.5 mm was much better. The most promising method of thinning apple trees cv. ‘Szampion’ was the use of MaxCel+Brevis, at fruitlets diameter of 10-12 mm. The yield expressed by the number of apples on a tree was much smaller than in the control, but total yield did not differ from the total yield of the control trees. Apples in this treatment were characterised by the highest mass and length, as well as large diameters. In the fruits of this treatment, there was no significant reduction in flesh firmness relative to the control, and they had the highest dry matter content.