A comparison was made between the amount of airborne pollen collected by Burkard airsampler and the allergenic activity of particles trapped on glass fibre filters in an Accu-Vol high-volume airsampler. The comparison was made throughout the pollen seasons 1986 to 1989. Both airsamplers were operated 24 h a day. They were placed less than 5 m apart, and estimation of the pollen amount was made on a day-to-day basis during the pollen seasons, and on a weekly basis outside the seasons. The occurrence of the 3 clinically most important allergenic types of pollen, birch, grass, and mugwort, was analysed, and close correlations between the 2 sampling techniques were found (rs 0.5-0.8, p < 0.001). The detected range of counted pollens/m3 was: birch 0-1075, grass 0-156, and mugwort 0-44. By immunochemical analysis we found the corresponding amounts to be 0-80, 0-8, and 0-1 SQ-U/m3, respectively. Pollen counts and immunochemical estimation were compared with the symptom score recordings of allergic persons for birch season 1989 and for grass seasons 1986, 1988, and 1989. A close correlation was found for both sampling techniques for the grass seasons in 1986 and 1989 (rs 0.51-0.61, p < 0.001-0.0001), but a less significant correlation was found for the 1988 grass season, and for birch in 1989 (rs 0.24-0.34, p < 0.001-0.05).