Not only are there large number of guides, protocols and other support tools available for the clinical decision-making process in the Spanish National Health System, but there is also a major degree of variability among them, reflecting inconsistencies and low quality of those documents. This study is aimed at conducting all inventory of the Clinical Practice Guideline assessment scales and clinical analysis tools and to propose a scale or set of criteria for assessing the quality of the Clinical Practice Guidelines put out in Spain. A systematic search of critical evaluation scales was conducted. The inclusion criteria and the concordance analysis of the items by three evaluators were independently applied. The discordances were resolved by explicit consensus. Ten suggested critical assessment scales and sets of criteria from eleven institutions were identified, eight of which consist of scales and tools proposed for assessing the quality of the Clinical Practice Guidelines, the other two being proposals for assessing the implementation and inclusion of the Clinical Practice Guidelines in a register. In the comparative analysis, the criteria most often repeated on the scales analysed were related to the areas included in the AGREE Instrument. The areas considered in most of the critical assessment scales were the same as those of the AGREE Instrument. Although this tool does not take in criteria for guide implementation assessment purposes, it is considered suitable for use in the assessment prior to inclusion to the national CPG register.