The UK Highways Agency has published Advice Notes on the Non-Destructive Testing of Highway Structures. This paper describes the background to these Advice Notes, how they were developed and trialled, what their objectives are, and how they will be extended in the future. The contents are based on research on various NDT techniques funded by the Highways Agency. The resulting reports have been worked up by the Highways Agency's NDT Steering Committee into Advice Notes to enable these techniques to be used for the investigation of Highway Structures. The Advice Notes are formed of three tiers; the first tier consisting of General Guidance on NDT; the second tier comprising Areas of Application; and the third tier covering NDT Techniques. This three tier format enables the Advice Notes to be readily extended in the future to cover further areas of application and other NDT techniques.