Many airborne pollen grains and fungal spores are important biopollutants responsible for human respiratory allergy. In the conditions of România the most important cause of pollinosis is allergenic pollen of some deciduous trees as well as grasses and weeds. The measurements of pollen concentration in the aeroplankton of Timişoara were carried out in 2003 by the volumetric method. The highest concentrations are noted in April and August. A total of 23 types of pollen taxa were recorded in the air of the study area in the 2003-year: Acer, Alnus, Ambrosia, Artemisia, Betula, Carpinus, Chenopodiaceae/Amaranthaceae, Corylus, Fraxinus, Juglans, Morus, Pinaceae, Platanus, Plantago, Populus, Poaceae, Rumex, Salix, Quercus, Taxaceae/Cupressaceae, Tilia, Urtica, Ulmus. The highest values of annual total of pollen grains in a group of trees were reached by Populus and Betula, as well as in a group of grasses and weeds – Ambrosia, Urtica and Poaceae. Trees pollen predominantly contributed to the total pollen sum with a percentage of 53.56%, followed by herbs 37.54% and grasses 8.9%.