The pathway leading to hyperphosphorylated, insoluble and filamentous tau protein (PHF-tau) is at the centre of many human neurodegenerative diseases such as Alzheimer's disease (AD). The development of selective PET radiotracers targeting PHF-tau is critical for early and accurate diagnosis, as well as the successful development of disease-modifying therapies. For AD, selective PET radiotracers for β-amyloid are already available, and potential PHF-tau tracers are emerging as new-generation biomarkers. This article summarizes the development scenario of PET PHF-tau radiotracer and their potential role for diagnosing and treating AD, as well as future clinical applications in regards to differential diagnoses of tau-related non-AD neurodegenerative diseases.