Miniature cyclone separators have important applications in the detection of bioacrosols in ambient air. Experiments have shown that miniature cyclones can be used to collect bioaerosol particles with high efficiencies and with an acceptable pressure drop in the separation unit. However, performance correlations based on large cyclones are not valid for small-scale cyclones. In this study, the effect of the scaling of the cyclone and four different geometric parameters-conical length, vortex-finder length, vortex-finder diameter and underflow diameter-on the performance of a cyclone separator is investigated. Based on the results of numerical computations, generalized performance correlations, relating the pressure coefficient and the total collection efficiency to dimensionless geometric and operational parameters are developed.