The deposition of alkaline and acidic aerosol compounds on a Douglas fir forest was measured by washing natural and artificial branches and using a certain type of Petri-dish sampler. The results were scaled to deposition on the entire canopy, using data on the vertical distribution of the leaf area index and the wind velocity profile within the canopy. The results are, within the uncertainty range of the measurements, comparable to those of net throughfall measurements corrected for canopy exchange, except for the results concerning Na and Cl. The calculated deposition velocities are high because of the high LAI and the large fraction of alkaline elements within the coarse-aerosol fraction. Theoretical data on aerosol deposition velocity compare well with the experimentally obtained values.