In recent years much progress has been made in radiological methods, in dosimetry, and in the knowledge of radiation effects. The ICRP has increased its risk estimates, and in addition, more extensive information has become available on the effect of age at exposure, on gender differences, on the magnitude of risk and on the consequences on in utero irradiation. The objective of Radiological Protection in Biomedical Research is to provide advice to individuals planning such research, those involved in issuing general rules of conduct, and those engaged in evaluation of specific research projects. The report should also be made available to those who may become the subject of investigations (patients, volunteers). Published with this report is a Summary of the current ICRP Principles for Protection of the Patient in Diagnostic Radiology. This has been prepared to encourage medical professionals to become aware of and to utilise those basic principles, and is an update of a previous summary that appeared in ICRP Publication 57 (1989). Finally, the report includes Addendum 1 to ICRP Publication 53 on Radiation Dose to Patients from Radiopharmaceuticals; this part of the report however is superseded by ICRP Publication 80.