The reason to develop and use Clinical Imaging Guidelines (CIG) is, simply, to improve patient care. CIG development and use are based on the principle that imaging use is not always optimal; reasons for this include lack of expertise (with either the clinical concern or the available imaging modality), nonmedical reasons for requesting the study (medicolegal concerns, possible financial gain), lack of available resources, and expediency. The use of CIG potentially helps in all of these areas, by providing guidance based on high-quality literature and supplemented by expert opinion. CIG answer the question: which, if any, imaging study would be most helpful in this specific clinical situation? The answer is based on assessment of the risk–benefit ratio for the patient. Benefits of imaging are often obvious. Risks, however, also exist, and include the effects of radiation (admittedly difficult to quantify), complications due to contrast agents or the technology (e.g., MRI-related accidents) or other medications, and the possible consequences of unexpected incidental findings that may require evaluation and intervention. The cost to society as well as top individuals must be considered.There are clear steps in the development of any clinical guidelines. First, there must be a sound, reproducible, transparent methodology. Then, specific clinical conditions must be defined, including consideration of their incidence, impact (e.g., success of diagnosis, treatment, and outcomes), and cost to the system. There must be sufficient high-quality literature available to justify review and guideline creation. The literature must be comprehensively and systematically reviewed and summarized. The summary and the topic as a whole must be reviewed by a group that includes all relevant stakeholders. Recommendations must be based to as a great an extent as possible on the literature, supplemented by expert opinion. The guideline must be regularly updated. Any potential conflicts of interest must be clearly presented. Overall, the methodology must follow accepted norms and be reproducible and transparent.There are many challenges in developing and using CIG. In addition to accurate representation and synthesis of what is known, these include adaptation to specific groups of patients and medical systems—what is appropriate for a pediatric age group, for example, may not be appropriate for adults. What works in a fee-for-service developed nation with all imaging modalities available may not work in a rural society with limited equipment and expertise. Finally, the primary goal of CIG is to improve patient care, so they have some clear value for educational purposes, of trainees, non-imagers, patients, families, and regulators. Their greatest use lies in incorporation into the process of requesting imaging studies, to guide appropriate use. This includes prevention of overuse and also elimination of under-use. As such CIG are now widely used in the physician order entry component of electronic health records.