Granular filtration of polydispersed aerosols were studied experimentally. The objectives of the study were to investigate the effect of deposited particle size on the increase of the unit collector efficiency and to quantify the increase for predicting filter performance. An algorithm for determining the effluent concentration histories of polydispersed aerosol filtration was presented. Together with the correlations developed in this work, prediction of filter performance can be made readily. Good agreements between experiments and predictions based on the correlations established in this work were observed.