Some of the cognitive impairments of schizophrenia are already detectable before the onset of the disease, and could help to identify individuals at higher risk of psychosis. In patients with schizophrenia, semantic verbal fluency (VF) is more impaired than phonological fluency. We investigated whether the same profile is present in young patients at Ultra High Risk of psychosis (UHR). One hundred and fifty six young patients (15–30y.o.) consecutively seeking help at our specialized youth mental health center with no definite psychiatric diagnoses were recruited and assessed with the CAARMS. Individuals meeting the criteria for UHR were compared to the remaining patients considered as Help Seeker Controls (HSCo). UHR individuals had a lower mean total semantic fluency score than HSCo. This effect was significant for each semantic category (‘animals’ and ‘fruits’). By contrast, there were no differences in phonological fluency scores between UHR and HSCo either in the total score or when each letter (‘P’ and ‘R’) was considered separately. Semantic but not phonological VF differentiated UHR individuals from non-psychotic help-seeking young adults. These results suggest that semantic deficits are present during the prodromal phase, prior to clinical expression of full-blown psychosis, and suggest that prodromes could be associated with alteration in temporal brain areas.