The International Commission on Radiological Protection has given general guidance on the precautions to be taken in the storage, handling and disposal of unsealed radioactive material in hospitals and medical research establishments in ICRP Publication 5. The present publication replaces the previous recommendations of the Commission given in ICRP Publication 5 and is primarily directed towards the competent national authorities. By utilizing the practices outlined in the present report, it should be possible to keep radiation doses well below the maximum permissible levels recommended by the Commission. National regulatory authorities should, however, draw up the necessary local standards and control procedures. The Commission believes that the information given can be utilized also by the local medical and research institutions and to some extent be applicable to other types of laboratories where radioactive substances are used. This report is concerned with the problems which arise owing to the use of unsealed radioactive substances in therapy, diagnosis and research.