The Scottish Intercollegiate Guidelines Network (SIGN) has developed a new system for grading recommendations in evidence-based clinical guidelines. The previous grading system, based on the US Agency for Healthcare Research and Quality (AHRQ), was criticized for its focus on randomized controlled trials (RCTs) and lack of consideration for the methodological quality and applicability of the evidence. The revised system aims to maintain the link between the strength of evidence and the grade of recommendation while allowing for the best available evidence to be weighted appropriately. Key changes include combining study type and quality ratings in the evidence level, clarifying the grading of recommendations, and extending the grades from three to four categories. The new system emphasizes the importance of methodological evaluation, evidence synthesis, considered judgment, and a clear presentation of the evidence supporting the recommendations. Early results suggest that grade A recommendations will become relatively rare, and grade B will be the best achievable in many areas. The review group expects further research to validate the effectiveness of the new system.The Scottish Intercollegiate Guidelines Network (SIGN) has developed a new system for grading recommendations in evidence-based clinical guidelines. The previous grading system, based on the US Agency for Healthcare Research and Quality (AHRQ), was criticized for its focus on randomized controlled trials (RCTs) and lack of consideration for the methodological quality and applicability of the evidence. The revised system aims to maintain the link between the strength of evidence and the grade of recommendation while allowing for the best available evidence to be weighted appropriately. Key changes include combining study type and quality ratings in the evidence level, clarifying the grading of recommendations, and extending the grades from three to four categories. The new system emphasizes the importance of methodological evaluation, evidence synthesis, considered judgment, and a clear presentation of the evidence supporting the recommendations. Early results suggest that grade A recommendations will become relatively rare, and grade B will be the best achievable in many areas. The review group expects further research to validate the effectiveness of the new system.