Recent research has shown that both the speed and accuracy of novel motor skills improve during sleep in a process called consolidation. Such off-line learning in the absence of practice as yet has been experimentally observed only with learners performing relatively simple tasks. In the experiment we report here, we tested whether experienced learners performing a music skill obtain similar sleep-dependent improvements. Participants learned a 12-note melody on the piano, and recalled the melody following 12- or 24-hour intervals that either did or did not include sleep. We found significant sleep-dependent improvements in performance accuracy in the retests that followed intervals of sleep, and no significant improvements following intervals that did not include sleep. This is the first demonstration of consolidation-based enhancement of motor skills in the context of music. We did not find consistent sleep-dependent enhancements in performance speed, but we observed that temporal evenness improved in the absence of practice 24 hours after training. (Contains 4 figures and 1 note.)