Continuous monitoring of forest conditions have great importance for the ascertainment of the current changes in forest ecosystems and cause-effect relationships between the changes and the factors that affect the condition of the forest ecosystem. At the beginning of the eighties of the last century in Europe, due to the intensive destruction of forest ecosystems, it was necessary to analyse the impact of air pollution on the state of forest ecosystems and in 1985. the International Co-operative Programme on the Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) was established. The paper presents the results of monitoring of crown condition in the period from 2004 to 2016 on the plots of the first level of monitoring of transboundary air pollution effects on forests in Vojvodina. The observation og crown condition was performed on a total of thirteen plots. Additionally was assessed and analysed the impact of the biotic and abiotic harmful factors on the crown condition. The most noticeable damages were found on black pine and common oak trees. In these species is ascertained the low percentage of trees without defoliation and were recorded dead trees especially in common oak . Best condition was found for poplar and black locust. Studies have shown that harmful biotic and abiotic factors have a strong influence on the crown condition of trees.