Working memory (WM) performance in humans can be improved by structuring and organizing the material to be remembered. For visual and verbal information, this process of structuring has been associated with the involvement of a prefrontal–parietal network, but for non-verbal auditory material, the brain areas that facilitate WM for structured information have remained elusive. Using functional magnetic resonance imaging, this study compared neural correlates underlying encoding and rehearsal of auditory WM for structured and unstructured material. Musicians and non-musicians performed a WM task on five-tone sequences that were either tonally structured (with all tones belonging to one tonal key) or tonally unstructured (atonal) sequences. Functional differences were observed for musicians (who are experts in the music domain), but not for non-musicians – The right pars orbitalis was activated more strongly in musicians during the encoding of unstructured (atonal) vs. structured (tonal) sequences. In addition, data for musicians showed that a lateral (pre)frontal–parietal network (including the right premotor cortex, right inferior precentral sulcus and left intraparietal sulcus) was activated during WM rehearsal of structured, as compared with unstructured, sequences. Our findings indicate that this network plays a role in strategy-based WM for non-verbal auditory information, corroborating previous results showing a similar network for strategy-based WM for visual and verbal information.