In order to determine the primary cause of dieback and loss of tree growt and vitality in pure stands of Norway spruce at Kopaonik Mountain, dendrochronological methods were applied. Field sampling was carried out in 2016 at four sites in stands with various health conditions in which different forest management measures were applied. The annual amount of precipitation and precipitation during the growing season from 1980 to 2015 was approximately on the same level with a slight tendency of increase. However, the mean annual temperature and mean temperature during growing season had a significant increase. In the same period, the declining trend of growth was determined. Pearson's correlation analysis shows a clear relationship between the mean temperature during the growing season and the tree-ring widths from the sites where the tree mortality was determined. The influence of mean monthly temperatures and sum of precipitation on monthly level on the on the tree-ring growth of spruce trees was investigated. Bootstrapping correlation analysis showed that there were characteristic months in which monthly values of climatic variables have a direct impact on the annual tree-ring widths.