Pregroups had been conceived as an algebraic tool to recognize grammatically well-formed sentences in natural languages [3]. Here we wish to use pregroups to recognize well-formed chords of pitches, for a given definition of those chords. We show how a judicious choice of basic and simple types allows a context-free grammatical description. Then we use the robustness property to extend the set of well-formed chords in a simple way. Finally we argue in favor of an utilization of pregroups grammars for the recognition and classification of chord sequences.