Report 94 gives guidance for the acceptance testing and commissioning of radiotherapy linear accelerators and comprises a comprehensive account, including some of the most recent clinical facilities available on the linear accelerator, in a single volume.  The Report examines issues common to all installations such as management of the process, critical examination, electrical, mechanical and radiation safety, mechanical and optical tests, and dosimetric measurements.  Later chapters consider specific components of the modern linear accelerator including systems for multileaf collimation, electronic portal imaging, dynamic wedging, record and verify, intensity modulation and stereotaxis.  A comprehensive list of references is included.  The Report is a companion volume to IPEM Report 81 (Physics Aspects of Quality Control in Radiotherapy) and will be of particular interest to Radiotherapy Clinical Scientists, Clinical Technologists and Managers involved in the planning, acceptance testing and commissioning of the modern linear accelerator.