This publication provides information on the implementation of quality assurance and quality control programmes for the measurement of radioactivity related to the practice of nuclear medicine. It is based on the QA principles of ISO/IEC 17025, which describe the requirements that testing and calibration laboratories must meet to demonstrate that they have a quality system in place and are technically competent. This report provides information specific to implementing that standard at both the end user (clinic) and secondary radioactivity standards laboratory levels. If fully adopted, it will provide the user with all the information (including measurement procedures) necessary to carry out most tasks associated with routine radioactivity measurement, including maintaining the necessary documentation.