Implementation of a new medical diagnostic test is a complex process, with test validation an integral component that ties together many aspects of test implementation.  Performing a test validation can be daunting, but it doesn’t have to be if you follow a structured best practise approach. When trying to conform with standards such as ISO15189, the wording can cause some consternation when it describes the requirement for test validation to be “extensive as necessary”.  This article will attempt to provide a best practise approach to test validation by outlining a step-by-step process that can be easily adopted by the laboratory.