Using fMRI, ten improvising musicians were contrasted with 10 non-musicians to explore brain activations while playing by ear. Subjects either imagined playing the music they were listening to, without moving their hands, or assessed the performance verbally without actually speaking. Half of the music excerpts was familiar, the other half unfamiliar. Musicians exhibited significantly larger activation of bilateral premotor cortex and right parietal cortex. Activation of right posterior superior parietal cortex was elicited specifically by imagining that they were playing by ear.