This research paper presents a new 2-way double-type smartcard terminal's and a new system's design and development of the prescription order communication system (POCS) based on the Internet between the hospital and the pharmacy, on the public-key infrastructure (PKI), and on the concurrently parallel co-operation with both medical professional 's and patient's smart cards in the 2-way double-type terminal under the synchronized status, in order to control security and privacy of patients and to manage drug histories of them. Concurrently parallel co-operation method at the synchronized status has been proposed in order to merge the digital signature generated by a medical professional with a patient's prescription data, to control security and privacy of patients, and to manage drug histories of them. The digital signatures w itten by the medical professionals (doctors and pharmacists) holding and using their individually master smart cards are applied to all contents of the prescription stored on a patient's slave smart card at the synchronized status in the 2-way double-type terminal. Therefore, digital signatures for all prescriptions stored on the smart card should effectively be used to prevent being altered, forged, and reused by unauthorized users and being repudiated by medical professionals.