The estrogen derivative 16α-18F-fluoro-17β-estradiol (FES) is a PET tracer that has been used in a variety of preclinical and clinical studies to detect estrogen receptor (ER) expression, mainly in breast cancer, but also for other oncological indications. As a result of the success of these studies and the potential applications of the tracer, FES starts to be implemented in routine clinical practice. However, the number of centers using this tracer is still limited and many nuclear medicine physicians and medical oncologists are still unaware of the possibilities FES PET imaging offers. The aim of this article is therefore to give an overview of the main indications of FES PET in oncology and to provide recommendations on correct use of this imaging technique. This includes precautions that have to be taken for patient preparation, procedures for the acquisition of the scans, the physiological distribution of the tracer, factors that might influence tracer uptake and guidance for image analysis, quantification of tracer uptake, and reporting of the scans.