A universal separation efficiency (USE) for evaluating the separation characteristics of multicomponent, multi-product separation processes in mineral processing is proposed. The maximum universal separation efficiency attainable in the separation process data is designated as the universal separation index (USI). The proposed USE is superior to Rony's "extent of separation" index. The "extent of separation" index was developed largely for binary chemical processes and was extended to multi-component/product separation processes. In the case of N-components/products, the "extent of separation" index suffers a serious limitation in that it produces a zero value if there is stream splitting between any Two product streams, even if there is perfect separation of the remaining components in the remaining product streams. This limitation has been eliminated in the proposed USE, which produces a zero value only when there is stream splitting between "all" product streams. The USE is normalized, i.e.; it varies between 0 and 1, where the value of one represents total separation (complete spatial or physical isolation) of the components in the product streams. Several data sets are used to demonstrate the use of USE and USI in different mineral processing separation processes.