A self-identifying integrated circuit contains a primary function circuit and an immutable, unique identification code, which is presented at an output port thereof upon demand by, an external circuit. The unique identification code may be an N bit digital number or may be a response signal to an interrogating excitation signal. The circuitry to store the unique identification code is fabricated on a microscopic scale such as by a direct-write laser forward transfer of material process or by a laser ablation of select material process. The identification storage means may be disposed on a package substrate or on an integrated circuit die and is permanently encased within the integrated circuit package so as to be protected from alteration by external means.