Structured Analysis and Design Methodology is devised for general purpose application development and has been widely used in the industry. The methodology uses the Structured Specification to capture the design of an application. Unfortunately, the Structured Specification only has an informal definition and consequently, the correctness of a design cannot be easily verified. Prototyping has been acknowledged as an effective way to verify designs. Some attempts have been made to help generate prototypes from designs produced by the methodology. This paper contributes to this approach by providing a set of translation rules for deriving prototypes from the Structured Specification to Prolog programs. The proposal differs from previous attempts in two aspects. First, the specifications for which prototypes are generated are less restrictive and have richer semantics. Second, the translation rules facilitate automatic generation of full prototype and can be easily integrated into a CASE tool supporting the Structured Analysis and Design Methodology.