Evidence-based medicine (EBM) is defined as using the best available evidence for managing patients in daily healthcare practice. Although this approach has been applied successfully in many medical fields, it has not been addressed fully in the radiological discipline in general and nuclear medicine in particular. In this review, the concept of EBM has been introduced briefly and four steps of EBM practice have been explained. Asking answerable questions and finding the best evidence that constitutes the first two parts of EBM practice are explained in brief. The next two steps (appraising the available evidence and applying the best evidence) are explained in more detail. Since the bulk of nuclear medicine studies are of a diagnostic nature and most of the daily practice of a nuclear medicine specialist is involved in diagnosis, we have focused on the diagnosis studies. Systematic reviews are also explained to some extent. Appraisals of other kinds of study, such as interventional or prognosis studies, are not included in this review.