Abstract-This paper compares the performance of various rule-based classification systems. In the classification problems in this paper it is assumed that a misclassification cost is associated with each training pattern. Thus, the task of classification is to minimize the total sum of misclassification costs rather than to maximize the classification rate. Ifthen rules are being generated from a given set of training patterns. The differences between the classification systems used in this paper are (a) whether fuzzy sets or interval sets are used in the antecedent part of ifthen rules, and (b) how the consequent part of the if-then rules is determined. In the determination of the consequent part of if-then rules we consider cost-based and compatibility-based determination . In costbased determination, the consequent class of a rule is determined so that the misclassification costs is minimal over the covered training patterns by the antecedent part of the rule. On the other hand, in compatibilitybased determination the consequent class of an if-then rule is determined from the compatibility of training patterns covered by the antecedent part of the rule. The grade of certainty of the rules in both determination types is calculated by using the compatibility of training patterns from each class. In a series of computational experiments, we examine the performance of the classification systems for three real-world pattern classification problems.