The application of biometric devices and systems is experiencing significant growth, primarily due to the need for reliable authentication. Verification and validation techniques applicable to these systems are rather immature and ad hoc, yet the consequences of the wide deployment of biometric systems could be significant. In this paper we discuss an approach to validation and reliability estimation of a Fingerprint Registration Software. Our validation approach includes the following three steps; a) The validation of the source code with respect to the system requirements specification; b) the validation of the optimization algorithm, which is in the core of the registration system and c) the automation of testing. Since the optimization algorithm is heuristic in nature, mathematical analysis and test results are used to estimate the reliability of the image registration module.