Cities are ecosystems: - they are open and dynamic systems, which consume, transform and release materials and energy. Air pollution is a basic problem in today‘s world and exposure to ambient air pollution has been linked to a number of different health outcomes. Tackling ambient air pollution is crucial to achieve sustainable development and mitigating effects of climate change. Planting urban trees could reduce air pollution effect. Trees are important for monitoring and maintaining the ecological balance. Air pollution Tolerance Index determinations of trees are prime importance as with rapid increase in vehicular movements, urbanization and industries. Screening of trees for their sensitivity/tolerance level to air pollution is important for urban air pollution management strategies to maintain micro climates and ecological services. The main objective of the study was evaluation of air pollution tolerance index of selected tree species. Sensitivity and response of trees to air pollution is variable and agro- ecology dependent. In Ethiopia no significant studies had been conducted in this area particularly in bahir dar city. Under such a situation evaluating air pollution tolerance index of selected tree species in the study area had been relevant and topical issue. Mangifera induca (Mango), Grevillea Robusta (Grevilea), Borassus aethiopulm (Zembaba) and Azadrachta indica (Kinin zaf/ Neem) were selected for the study. Leaves of each tree species for each parameter were separately collected and extracted with different reagents. Ascorbic acid, total chlorophyll, leaf extract pH and relative water contents were characterized and computed together for the implication of air pollution tolerance index (APTI) of trees. The study displayed that Mangifera indica is relatively tolerant followed by Azadirachta indica Moderately Tolerant, Grevillea Robusta Intermediate Tolerant and Borassus aethiopulm sensitive with APTI value of 16.443±0.047, 12.963±0.021, 10.450±0.087 and 8.920±0.010 respectively. Trees having high indices are generally tolerant to air pollution and can survive on polluted air. Trees with low indices show sensitivity to air pollution. The tolerance and sensitivity vary among tree species. Planting trees based on their air pollution response is recommended. Keywords: Air pollution tolerance index, Tree species, Bio -chemical parameters, Tolerant, sensitive.