CLINICAL PRACTICE GUIDELINES IN THE CHILEAN HEALTH SECTOR REFORM: A CRITICAL ASSESSMENT OF THEIR QUALITY. Background: Clinical practice guidelines are widely used as tools for improving quality of health care. However, there is increasing concern about limitations in their development process conducting to inconsistent recommendations. During the last decade the use of guidelines has been promoted in the Chilean health system, but their quality has not yet been evaluated systematically. Aim: To assess the quality of clinical practice guidelines developed by the Chilean guidelines program. Material and methods: All the guidelines developed by the Chilean program between 2005 and 2009 were retrieved from the Ministry of Health website. Each guideline was assessed independently by three appraisers using the Appraisal of Guidelines, Research and Evaluation (AGREE) instrument. Standardized scores were obtained for each dimension in each guideline and across the whole set of guidelines. Results: Sixty guidelines were assessed. The ‘scope and purpose’ dimension scored significantly higher (mean 82.2%, range: 25.9% - 100%) and the ‘applicability’ dimension scored significantly lower (mean 23.3%, range: 0% - 72.4%) than any other dimension. ‘Publication date’ was the only variable consistently associated with dimension scores. Conclusions: The quality of Chilean clinical practice guidelines is far from ideal. Although they seem to have a strong sense of purpose and vision, methodological procedures should be strengthened, especially those related to applicability.