This paper describes a new approximate approach for checking the correctness of the implementation of a protocol interface, comparing its lowlevel implementation with its high-level prototype. The possibility to validate protocol interfaces is extremely useful in many industrial design flows and the proposed methodology does not impose particular requirements and it is able to fit in existing design flows: the proposed approach is based on coupling a commercial simulator with a genetic algorithm that tries to disprove the equivalence of an implementation with its high-level prototype. The use of a commercial simulator guarantees a complete compatibility with current standards and the method is able to fit painlessly in an existing industrial flow. Moreover, the use of a genetic algorithm allows the analysis of large and realistic designs. Experimental results show that the proposed method is effectively able to deal with realistic designs, discovering potential problems, and, although ...