We address the question of how syntactic and prosodic factors interact during the comprehension of spoken sentences. Previous studies using event-related brain potential measures have revealed that syntactic phrase structure violations elicit an early left anterior negativity followed by a late posterior positivity (P600). We present recent experimental evidence showing that prosodic information can modulate these components and thus the syntactic processes they reflect. We conclude that the initiation of first-pass parsing processes is affected by the appropriateness of the prosodic realization of the preceding element.