The aim of the study was to compare the concentration of 3 allergenic taxa pollen (ash, birch and oak) in the cities of Lublin (eastern Poland) and Szczecin (western Poland) during the years 2004 and 2005 and examine correlations between weather factors and pollen concentration. The meteorological parameters analysed were maximum and mean air temperature, relative humidity, amount of precipitation and wind speed. Measurements were performed by the volumetric method (Lanzoni 2000 pollen sampler). Pollen seasons were defined as the period in which 95% of the total catch occurred. The pollen seasons of the studied taxa started earlier in Szczecin than in Lublin. In both cities much higher Betula pollen concentration and slightly higher Fraxinus pollen concentration were recorded in 2004 compared to 2005. But for Quercus, higher concentrations were recorded in Lublin and in Szczecin in 2005. Annual totals and maximum daily pollen grain concentrations of the tree taxa in question were higher in Lublin than in Szczecin. In 2005, maximum Betula and Fraxinus pollen concentrations occurred in each of the cities at the same time: in Lublin on 18 April, in Szczecin on 16 April. Among the meteorological parameters analysed, maximum temperature and relative humidity belong to the most important factors which affect ash, birch and oak pollen concentrations in the air.