An account is given of the patented technique of the rotational particle separator for separating solid and liquid particles of diameter 0.1 mu m and larger from gases. Attention is focussed on the working principle, fluid mechanical constraints, practical designs, separation performance, power consumption, dimensions, filter cleaning and costs. Furthermore, an overview is given of current developments to introduce this technique in industrial dust removal, in electricity generation and in the consumer goods market. The article concludes with a summary of the features which distinguish this technique from existing filtering methods.