Research report on deformation of annual rings is given in the thesis. Aim of the work - to perform an analysis of deformation of annual rings during obsolescence of tree. Tasks of the work - to perform a comparative analysis using borings made in 2004 and 1985 – 1986. To evaluate statistical reliability of deformation of annual rings. Object of the work - trees of Scotch pine (Pinus sylvestris L.). Methods of the work – methods of verification of statistical hypotheses and analysis of variance were used for data processing. Content of the work – verification of hypothesis that annual rings of pine is shrinking during the obsolescence of trees. Results: - difference of annual rings width is statistically reliable at two point of the interval investigated: nearby bark and in the central part of the stem, at the margin where sapwood is converting to heartwood. The shrinking reaches 0.2 mm within 5 annual rings. The biggest influence on shrinking of annual rings has distance of annual rings from the bark and age of tree.