A new system for grading recommendations in evidence-based guidelines has been developed by the Scottish Intercollegiate Guidelines Network (SIGN). The system aims to improve the clarity and reliability of guideline recommendations by linking the strength of the evidence to the grade of the recommendation. The previous system, based on the US Agency for Healthcare Research and Quality, had limitations, particularly in areas where randomised controlled trials were not feasible. The new system incorporates a more structured approach, including methodological evaluation, synthesis of evidence, considered judgment, and a grading system. The revised grading system combines study type and quality rating to determine the level of evidence. Levels of evidence are based on study design and methodological quality. The strength of the evidence is influenced by the study's design and execution, with checklists used to assess methodological quality. The system includes a revised grading system with four categories (A, B, C, D) based on the strength and consistency of the evidence. The process involves evaluating the methodological quality of individual studies, synthesising evidence into an evidence table, and making a considered judgment about the relevance and applicability of the evidence. The grading system is designed to ensure that recommendations are based on the best available evidence and that the link between evidence and recommendation is clear. The new system includes checklists for evaluating different types of studies, including diagnostic tests. These checklists are based on validated models and have been adapted to meet SIGN's requirements for balance between methodological rigor and practicality. The system is intended to provide a clear and unambiguous way for guideline developers and users to understand the link between the strength of the evidence and the grade of the recommendation. The system has been tested and refined to ensure clarity and consistency. Early results suggest that the new system meets its objectives.A new system for grading recommendations in evidence-based guidelines has been developed by the Scottish Intercollegiate Guidelines Network (SIGN). The system aims to improve the clarity and reliability of guideline recommendations by linking the strength of the evidence to the grade of the recommendation. The previous system, based on the US Agency for Healthcare Research and Quality, had limitations, particularly in areas where randomised controlled trials were not feasible. The new system incorporates a more structured approach, including methodological evaluation, synthesis of evidence, considered judgment, and a grading system. The revised grading system combines study type and quality rating to determine the level of evidence. Levels of evidence are based on study design and methodological quality. The strength of the evidence is influenced by the study's design and execution, with checklists used to assess methodological quality. The system includes a revised grading system with four categories (A, B, C, D) based on the strength and consistency of the evidence. The process involves evaluating the methodological quality of individual studies, synthesising evidence into an evidence table, and making a considered judgment about the relevance and applicability of the evidence. The grading system is designed to ensure that recommendations are based on the best available evidence and that the link between evidence and recommendation is clear. The new system includes checklists for evaluating different types of studies, including diagnostic tests. These checklists are based on validated models and have been adapted to meet SIGN's requirements for balance between methodological rigor and practicality. The system is intended to provide a clear and unambiguous way for guideline developers and users to understand the link between the strength of the evidence and the grade of the recommendation. The system has been tested and refined to ensure clarity and consistency. Early results suggest that the new system meets its objectives.