There are many differences between verbs and nouns-semantic, syntactic and phonological. We focus on the semantic distinctions and examine differences in performance in both normal control subjects and individuals with aphasia. In tasks requiring production of particular semantic categories and categorisation of given verbs and nouns, control subjects produced fewer verbs than nouns and were slower and less accurate in verb categorisation. Patients who had shown a verb deficit in naming also had particular difficulties producing both verbs and nouns of relatively low imageability. In reading and writing, some patients exhibited poorer performance with verbs than nouns, even when verb/noun homonyms were used. When imageability was controlled, however, no dissociation was shown. We conclude that in simple single word tasks imageability must be controlled to eliminate this as a factor in apparent verb deficits. Other semantic factors, however, could affect performance, particularly when tasks involve the relationships between category exemplars.