Congenital amusia is a lifelong disability that prevents afflicted individuals from enjoying music as ordinary people do. The deficit is limited to music and cannot be explained by prior brain lesion, hearing loss, or any cognitive or socio-affective disturbance. Recent behavioral results suggest that this disorder is critically dependent on fine-grained pitch discrimination. Here, we present novel electrophysiological evidence that this disorder can be traced down to a right-lateralized N2-P3 response elicited by pitch changes. This abnormal brain response begins as early as 200 milliseconds after tone onset and may serve as a marker of an anomaly in music acquisition.