The role of the physicist in radiation protection in medical practice is briefly reviewed by considering the scientific, educational and managerial aspects of the provision of radiation protection services to medicine. The scientific contributions are examined in five areas of application: radiotherapy, nuclear medicine, diagnostic radiology, protection of the public (including environmental considerations), and dosimetry and personal monitoring. The requirements for the protection of staff, patients and the public are identified. Three examples of new or developing techniques which influence radiation protection requirements are described. In the first, the use of remote afterloading techniques in brachytherapy has reduced staff doses because of the ability to remove sources from patients before nursing procedures are carried out. In the second, the increasing use of interventional procedures in diagnostic radiology can give rise to radiation protection problems for the radiologist, who may be exposed at short distances and for relatively long times to secondary radiation from the patient under fluoroscopic screening. Finally digital imaging techniques offer promise of improved extraction of image information, thus affecting benefit-detriment judgments.