Good Clinical Practice (GCP) guidelines, with an emphasis on quality and validation of processes and data, must be applied to the use of imaging in clinical drug development. All participants, including the sponsor, principal investigator, site staff, quality assurance centers, and contract research organizations, must be cognizant of the need for application of these principles to their activities related to the imaging programs. This article discusses the various aspects of GCP as they need to be applied to the use of dual X-ray absorptiometry (DXA) for bone densitometry and X-rays for vertebral fracture assessment in clinical trials for osteoporosis, as well as research and private practice settings. The theory of proper audit conduct to verify clinical trial data is presented.