The experiment was carried out with in vitro propagated 'MM 106' apple-rootstock plantlets. The transpiration of the plantlets was examined, and the changes followed by SEM analysis. Data about the transpiration intensity of the acclimatized plants, of its value under different conditions of relative humidity and influenced by the existence of roots, as well as by the degree of acclimatization are presented. Leaves were also examined and it was found, that stomata of in vitro developed leaves closed slowly, and the number of stomata of newly developed leaves decreased. It is also shown, that in vitro propagated roots, generally, lose their hairs during acclimatization, but these roots are all the same important, as new roots of full value develop out of them.