This paper presents an enhanced user interface, “Fingerprint User Interface (FpUI),” that exploits fingerprint identification technology, and discusses its application to information systems, specifically to a mobile authentication terminal for networked services and digital appliances. FpUI utilizes information regarding not only who put a finger on its sensor but which specific finger it was. A user can assign commands, data objects, status, or personalized settings to individual fingers for user-friendly direct manipulation. A mobile terminal, “Pocket-PID,” with fast, accurate fingerprint identification capability is proposed which features (1) an easy-to-use FpUI, (2) high security (the identification function is totally enclosed within the unit, which authenticates a user's identity without the possibility of actual fingerprint data being disclosed), and (3) secure and usable non-contact communication capability which facilitates implementation of networked services based on biometric user identification.