Current image retrieval systems do not provide users with adequate interfaces able to reduce the semantic gap existing between the high-level semantics of images (as perceived by the users) and their low-level machine representation. In this paper, we present MuSIQUE, a multi-system user interface, mainly designed for experimental purposes, that makes it possible to compare different systems into an integrated environment. By critically reviewing limits of the interfaces of stateof-the-art image retrieval systems, we have been able to integrate into MuSIQUE all the advanced functionalities of such systems and, at the same time, to overcome their shortcomings. A detailed description of the interface features of MuSIQUE, concerning querying, visualization, and browsing, is reported. Moreover, a brief example of MuSIQUE in action is shown, aiming to illustrate the effectiveness of the proposed facilities.