We used event-related functional magnetic resonance imaging (erfMRI) to investigate the neural basis of biological and syntactic gender integration during pronoun processing in German sentences about persons or things. German allows for separating both processes experimentally. Overall, syntactic processing activated areas adjacent to Broca's area (BA 44), whereas processing of the biological sex, in addition, involved the supramarginal gyrus (BA 39). A previously reported event-related potential study using identical material suggests that syntactic and semantic information is integrated 400-700 ms after target onset, visible in both cases as a P600 but with different effect sizes. The fMRI and ERP results illuminate that pronoun processing involves a highly dynamic spatiotemporal integration of syntactic and biological information depending on the type of the antecedent and whether or not a violation is involved. The results are discussed in the context of cognitive models of pronoun processing.