In order to test the language-specificity of a known neural correlate of syntactic processing [the P600 event-related brain potential (ERP) component], this study directly compared event-related potentials elicited by syntactic incongruities in language and music. Using principles of phrase structure for language, and principles of harmony and key-relatedness for music, sequences were constructed in which an element was either congruous, moderately incongruous, or highly incongruous with the preceding structural context. A within-subjects design using 15 musically-educated adults revealed that linguistic and musical structural incongruities elicited positivities which were statistically indistinguishable in a specified latency range. In contrast, a music-specific ERP component was observed which showed antero-temporal right-hemisphere lateralization. The results argue against the language-specificity of the P600, and suggest that language and music can be studied in parallel to address questions of neural specificity in cognitive processing.