Although the right hemisphere is capable of comprehending words, to what extent andunder what circumstances this contributes to normal natural language comprehensionhas remained obscure. The positron emission tomography (PET) functionalneuroimaging experiment reported here showed that right hemisphere inferior frontalgyrus and dorsolateral prefrontal cortex are activated while subjects read temporarilyambiguous sentences in which the less preferred meaning of the word must finally bechosen. This result demonstrates that the right hemisphere is indeed involved in normalsentence comprehension under some circumstances. We relate this evidence to data fromright hemisphere damaged patients which suggests that the right hemisphere is involvedin revising meanings more generally and to neuroimaging evidence that the right frontallobe is active in verbal short-term memory tasks.