A new set of experimental data on the particle collection efficiency of small cyclones operating at high flowrates is reported. Seven different cyclones were studied systematically covering a flowrate range 60-1101 min(-1) and a particle size range 0.026-3.6 mu m. Special emphasis was given to the effects of the cylinder height and of the exit tube length on the particle collection efficiency. The length ratios of the cylinder height and exit tube length to the cyclone body diameter were varied from 0.75 to 4.5 and from 0.5 to 1.5, respectively. The experimental results suggest that the flowrate plays a significant role in cyclone collection efficiency. High flowrate can help to collect fine particles. As the cylinder height is increased, the collection efficiency increases. However, when the cylinder height is increased excessively, the collection efficiency appears to decrease to certain extent. An optimized exit tube length was also observed. Pressure drop decreased substantially either as the cylinder height became longer or as the exit tube length became shorter. It was also found that the difference between the cyclone cylinder height and the exit tube length affects the particle collection characteristics significantly.