Metabotropic glutamate receptors (mGluRs) belong to a family of G-protein coupled receptors involved in the modulation of fast excitatory transmission. In particular, the subtype-5 receptor (mGluR5) was found to be an attractive target for the treatment and diagnosis of variety of psychiatric and neurological disease including anxiety, depression, epilepsy, drug addiction, and Parkinson's disease. Positron emission tomography (PET) is a highly sensitive imaging technique that holds great potential for the diagnosis of a brain disorder. In the study published in the American Journal of Nuclear Medicine and Molecular Imaging, a (18)F labelled PET probe was developed targeting mGluR5. This paper represents the efforts and challenges on the design and development of novel PET tracers for mGluR5 imaging.