Large-scale electronic transaction systems, such as ATM networks and E-commerce applications, place high demands on biometric identification systems. Users must be identified rapidly, securely (few false accepts), and reliably (few false rejects). These demands are typically fulfilled by the use of microscopic morphological features because the largely random nature of their morphogenesis produces highly unique phenotypes. However, the microscopic scale of such biometric features usually requires contact or close proximity of the imaged tissue to the sensor, which can impede the user acceptability of the identification system. We have solved this problem cost-effectively by developing a real-time active vision system that allows us to image the microscopic features of the human iris at a comfortable distance, automatically and without user effort. The result is a high-accuracy iris identification system that is intuitive and easy to use and that has already been fielded in several pilots by banks in Europe, Asia, and the United States.