This study examined the musical processing in a professional musician who suffered from amusia after a left temporo-parietal stroke. The patient showed preserved metric judgement and normal performance in all aspects of melodic processing. By contrast, he lost the ability to discriminate or reproduce rhythms. Arrhythmia was only observed in the auditory modality: discrimination of auditorily presented rhythms was severely impaired, whereas performance was normal in the visual modality. Moreover, a length effect was observed in discrimination of rhythm, while this was not the case for melody discrimination. The arrhythmia could not be explained by low-level auditory processing impairments such as interval and length discrimination and the impairment was limited to auditory input, since the patient produced correct rhythmic patterns from a musical score. Since rhythm processing was selectively disturbed in the auditory modality, the arrhythmia cannot be attributed to a impairment of supra-modal temporal processing. Rather, our findings suggest modality-specific encoding of musical temporal information. Besides, it is proposed that the processing of auditory rhythmic sequences involves a specific left hemispheric temporal buffer.