 Abstract this paper provides an overview of the current state of the art in radiochemistry for positron emission tomography, PET. It covers the most common chemical transformations used for the synthesis of PET traces, including the use of biologicals for PET imaging, and highlights some of the most successful probe discoveries for molecular imaging with PET. The paper also discusses the use of translational and scalable radiochemistry concepts that have been entered into clinical use. This article was authored by Jen Rowe, Ahmed Haider, Trolls E. Jefferson, and others.