Airborne concentrations of pollen fromBetula(birch), Poaceae (grasses) andArtemisia(mugwort) are compared during a seven year period (90–96) with respect to both quantitative and seasonal aspects, at three different sampling sites, one in Estonia (Tartu) and two in Sweden (Stockholm and Roma on the island of Gotland). All three taxa occur in the region and are well‐known causes of allergic sensitisation. The annual total and peak values of birch, grass and mugwort pollen were found to be much higher in Tartu than in Stockholm and Roma. Both the birch and the grass pollen seasons ended later in Stockholm than in Roma and Tartu. The mugwort flowering season always began earlier in Stockholm than at the other sites, and more days elapsed between start day and peak day in Stockholm than in Tartu.