The article shows the results of the research into marketability evaluation of sour cherry (Prunus cerasus L.) fruits, treated with chitosan solution. To achieve this goal, fruits were treated with 0.5 % or 1 % chitosan solution, and stored at 5 °C for 21 days. To assess the shelf life of fruit, physical and chemical parameters were determined: mass loss, reduction of sugar, titrated acidity and ascorbic acid content. Treatment with chitosan solution significantly reduced the mass loss, content of sugar, acids, ascorbic acid and respiration rate. The treatment with chitosan solution extended the shelf life and improved the quality of sour cherry fruit.After 21-day storage of sour cherries, mass loss was 4.6 % with the product output accounting for 85.5 %. The obtained results are approved by physiological and chemical changes in the fruits during storage: respiration rate of fruits decreases, loss of sugar does not exceed 6.7 %, acids – 33 % and ascorbic acid – 18 %.It has been found that post-harvest treatment with 1 % chitosan solution has a positive influence on commercial quality of sour cherry fruits.