['This study aimed at defining the characteristics of a population of patients diagnosed with first-episode psychosis (FEP), and accessing for the first time a center for early intervention in psychosis in the health district of Milan and its surroundings.', 'Patients were included in the study from January 2007 to December 2008; criteria: first contact with any public mental health service of the catchment area for a first episode of schizophrenia or related syndromes according to the ICD-10 criteria. Cluster analysis was used to divide patients into groups based on the main socio-demographic and clinical characteristics at presentation.', 'Overall, 91 FEP patients were enrolled in the study. Two clusters were identified, which differed principally by symptom profile. Patients in cluster 1 (n=36) had severe agitation, and a history of alcohol and/or substance abuse at presentation more often than those in cluster 2 (n=55), who were more likely to suffer at presentation from severe depression or apathy, anxiety, poor self-care, functional or work impairment and severe social withdrawal. After six months of treatment patients improved on almost all symptomatic dimensions on the Health of the Nation Outcome Scale and the Brief Psychiatric Rating Scale, with greater improvement in cluster 1 than in cluster 2.'] Are patients With First-Episode Psychosis a Homogeneous Population : Implications for Treatment?