Functional neuroanatomy of the processing of morphologically complex words was studied by measuring regional brain activity by positron emission tomography (PET) during encoding of auditorily presented inflected versus monomorphemic Finnish nouns. Significant increases of activation occurred particularly in the left inferior posterior frontal lobe, corresponding to Broca's area. This suggests that besides their role in the production of grammatical morphology documented earlier, Broca's area and adjacent regions are important for the input processing of morphologically complex words.