Abstract. Evidence-based medical guidelines contain a collection of recommendations which have been created using the best clinical research findings (a.k.a. evidences) of the highest value to aid in the delivery of optimum clinical care to patients. In evidence-based medical guidelines, the conclusions (a.k.a. recommendations) are marked with different evidence levels according to quality of the supporting evidences. Finding new relevant and higher quality evidences is an important issue for supporting the process of updating medical guidelines. In this paper, we propose a method to automatically identify all evidence classes. Furthermore, the proposed approach has been implemented by a rule-based approach, in which the identification knowledge is formalized as a set of rules in the declarative logic programming language Prolog, so that the knowledge can be easily maintained, updated, and re-used. Our experiments show that the proposed method for identifying the evidence quality ha...