In the period of 2008 – 2010, it was studied the influence of foliar fertilization on the development of foliar surface and yield of apple trees. The investigation included the varieties Golden Delicious, Idared and Florina of 8 years old, grafted on M 26 rootstock, planted on a distance of 4x2 m and used as fertilizer 46% Urea in concentrations from 0,4% to 1,2% in different stages of fruit development, Poly-Feed (NPK 19:19:19 Mn, Mo, Fe, Cu, Mg, Zn) of 0,1% and CaCl2 of 0,5% to 0,7% concentration. The leaf surface varied depending on the variety and concentration of foliar fertilizers (Urea 46%). The largest leaf surface - 15.5 m2 - was obtained for the variety Golden Delicious in the group 4 where the spraying was performed with 46% Urea in concentrations of 0,6%, 0,9 %, 1.2% and the smallest was obtained in the control group where the leaf surface was of 11,3 m2.