A systematic study of the aerosol output was conducted from a modified commercially available Sinclair-La Mer-type monodisperse generator (TSI 3475) in the submicrometer region. The generator produces three different types of aerosols: sodium chloride, DEHS droplets condensed on NaCl nuclei and homogeneously nucleated DEHS droplets. The first two were found io be unimodal while the last one had a bimodal distribution. The aerosol droplet size distribution of the condensed aerosols was measured as a function of nuclei concentration, saturator temperature and saturator flow. It was concluded that when nuclei concentration decreases below similar to 10(6) cm(-3) homogeneous condensation is no longer suppressed and coexistence of two kinds of aerosol droplets of different size can be observed. The size distribution of all generated aerosols was measured by a scanning mobility particle sizer (SMPS).