Objective: To test the OQ-45.2questionnaire as an indicator of psychopathology and improvement in hospitalized patients, at the psychiatric unit of Hospital del Salvador, Santiago de Chile.Methods: A sample of 116 hospitalized patients was collected between August 2003 and September 2004.All of them had three OQ-45.2questionnaire measurements: at admission, at discharge, and during follow-up.The scores obtained were compared with progression of the psychiatric condition and co-morbidity.Results: All patients, except those diagnosed as suffering psycho-organic syndromes, had a statistically significant reduction in OQ-45-2 scores, when the results at admission and follow-up were compared.Even though this instrument has not been validated in psychotic patients, they showed improvement and their scores were below the average for this sample.Patients suffering psychiatric co-morbidity had higher scores, when compared with those with no co-morbidity and similar improvement.Conclusions: The OQ-45.2 questionnaire is a valid and sensitive instrument for assessing improvement in psychiatric inpatients.