As deciduous woody species make a large and significant portion of park plant communities, they are suitable for the programs of the urban environment biomonitoring. The study of the size and shape of pollen included 58 trees of the following 12 species: Aesculus hippocastanum L., Betula alba L., Ginkgo biloba L., Paulownia tomentosa Steud., Platanus x acerifolia (Aiton) Willd, three species of Quercus sp. (Q. robur L., Q. cerris L. Q. rubra L.) and four species of Tilia sp. (T. argentea Desf., T. x euchlora, T. grandifolia Ehrh., T. parvifolia Ehrh.). Pollen was collected in five parks in the area of Belgrade, three of which (Pioneer Park, Academic Park and Banovo Brdo Park) are located in the central city zone, while the park of the Palace of Serbia (SIV Building) and Topčider Park are in the wider urban zone. The pollen of birch, chestnut and pedunculate oak had smaller values of pollen length in the central city zone, due to the increased human activity, compared to the wider city zone. Ginkgo, chestnut and pedunculate oak didn`t have significantly different values of pollen width between the urban zones. The pollen of ginkgo, pedunculate oak and London plane had smaller mean values of the index of pollen shape in the central city zone. A reversed pattern of values, i.e. higher values in the central city zone, was obtained for the length of the ginkgo pollen and the width of the London plane pollen. The index of pollen shape in chestnut didn’t show any statistically significant differences between the city zones. The results of the analysis of variance confirmed statistically significant differences between the city zones for the length and width of pollen, and the index of pollen shape. The share of phenotypic variability caused by the differences in the environmental conditions between the zones (differences between the parks) was statistically significant for the analyzed pollen properties. Based on the preliminary results, it can be concluded that the increased environmental pollution in the central city zone leads to a reduction in the size of pollen. Therefore, future monitoring projects can use this property as an indicator of the change in the morphology of pollen under the influence of stress induced by conditions of urban environment.