Neurocognitive dysfunction in patients presenting psychotic symptoms for the first time has been repeatedly noted by researchers. However, there is still much diversity in data concerning the performance of these patients in specific cognitive domains and their degree of impairment. We used the Cambridge Neuropsychological Test Automated Battery (CANTAB), in order to administer a comprehensive battery of neuropsychological tests. A series of tests was selected measuring attention, memory, planning, inhibition, shifting ability, mental flexibility, working memory and visuospatial ability. The sample comprised 64 patients (37 male) with first episode of psychosis and 14 healthy individuals (9 male). Patients’ performance was lower in all cognitive domains, in relation to the performance of controls. More specifically, impairments in sustained attention (–.6 SD), memory (–.7 SD), planning (–.6 SD), working memory (–.7 SD), shifting ability (–.6 SD) and visuospatial ability (–.6 SD) were prominent. Also, patients presented a severe deficit in speed of processing (–.7 SD) and selective attention (–.6 SD). Our data confirms that patients in the first episode of psychosis present deficits in all cognitive domains. A more rigorous and thorough examination of specific subcomponents of cognitive abilities may be necessary in order to examine possible contributing factors as to specify the exact nature of cognitive deficits in first episode of psychosis.