In the period 2011-2016, on the ICP Level 2 plots for monitoring of the impact of air pollution on forest ecosystems in Vojvodina, phenological obsevations were performed in stands of the sessile and pedunculate oak. Phenological observations included 15 trees of sessile oak (Quercus petrea Matt/Liebl.) in stand from the area of Fruška gora (N 45°09'23,58"; E 19°48'38,61") at an altitude of 484 m and 15 trees of pedunculate oak (Quercus robur L.) from stand near the village Deronje (N 45°27'19,61"; E 19°10'23,85") at an altitude of 85 m. Within the phenological observations, the leaf unfolding phase and the leaf fall phase for the monitored period are presented. It is noticeable that leaf unfolding and leaf fall phase varied depending on the year of observation. For the researched six-year period, the longest period of leaf unfolding in sessile oak was 30 days, while the shortest period was 16 days, and in the pedunculate oak tree the longest period of leaf unfolding was also 30 days, and the shortest 7 days. The longest period of leaf fall for the sessile oak tree was 25 days and the shortest 13 days, while in the pedunculate oak tree the longest period of leaf fall was 29 days, and theshortest period was 8 days.