The validity and applicability of recommendations in clinical medicine are dependent on the design of studies upon which recommendations are based. Large prospective randomized controlled trials (RCT) generally provide the most reliable data to help guide our treatment decisions. However, analysis of decision-making in the field of hematologic malignancies indicates that only 24% of decisions can be based on randomized controlled trials. This lack of high-quality data to support many decisions in the treatment of malignant disorders underscores the need to evaluate the evidence that forms the backbone of guidelines themselves. As physicians are encouraged to conform to clinical guidelines, it is important that information be made available regarding the quality of data upon which these guidelines are based. We propose the development and use of a guideline quality score based on the quality of evidence supporting each decision in a guideline. By linking the quality of evidence with specific recommendations, physicians will be in a better position to understand the strengths and weaknesses of practice guidelines. This linkage will also help physicians to streamline their efforts to obtain a new line of evidence when an existing one is not satisfactory.