The number of dual-specificity protein tyrosine phosphatases has grown considerably in the last few years, and thus it would be helpful to organize these novel enzymes. The simple term "VH1-like" or "dual-specificity" phosphatase does not adequately reflect the different subclasses within this new and important phosphatase subfamily. In this article, we review the salient features of dual-specificity phosphatases and propose a novel classification scheme of these enzymes based on their structural motifs. Classification of dual-specificity phosphatases based on their motifs should serve as a useful organizational framework for bringing together this now large subgroup of phosphatases. Moreover, this classification scheme may hold predictive value, since some of these motifs may hold the key to new, undiscovered functional properties.