Presenting Author details:bobes@uniovi.es Avda. Julián Clavería 6, 33006 Oviedo, Spain, Tel.: +34 985 103605; fax: +34 985 103606. Background: Few papers approach the prevalence of cognitive effects among patients with schizophrenia. This data would provide information of utility in clinical practice. Our objective is to estimate the prevalence of cognitive dysfunction in a sample of ambulatory patients with schizophrenia. Methods: Transversal study of a sample of ambulatory patients during a routine follow-up visit in mental health centres. The selection criteria included a diagnosis of schizophrenia according DSM-IV-TR, maintenance treatment with second generation antipsychotic, for at least 6 months. Information recorded: functional status, clinical status and degree of disability by means of the WHO-DAS-S disability scale. Cognitive examination included domains related to functional outcome variables according to the MATRICS review (i.e. Working Memory, Executive Function, Verbal Logic Memory and Speed of Processing Information). The battery consisted of 4 well-known subtests. Results: The sample consisted of 672 patients in 232 centers. Only 12.5% had been cognitively assessed in the past. Speed of Processing Information was the most prevalently affected domain, with 38% of the patients showing performance less than 1.5 standard deviation (SD) from the mean, followed by 25.2% with affected Verbal Logic Memory and 21.1% with Working Memory. Cognitive performance was related to the patient's functional disabilities in different areas. Patients currently in employment showed better cognitive performance in all domains. Conclusions: Cognitive dysfunction in schizophrenia follows a heterogeneous pattern. Its assessment with objective methods is important for advising on functional aspects. The proposed battery is sensitive to the patient's functional disability and employment status. Acknowledgement: This study has been founded by Sanofi-Aventis. The authors thank M. Puig, S. Zaragoza and B. Gancedo from PSYNCRO for their contribution to the project.