As an integral part of a quality assurance programme, this survey was undertaken to establish precise details of breast radiation techniques used within centres expressing an interest to participate in the START Trial--a U.K. multi-centre randomised trial of different dose fractionation schedules for breast cancer. A questionnaire was circulated between November 1997 and January 1999 to 56 U.K. radiotherapy centres. This covered specific details of patient immobilisation, technique and dose fractionation when treating breast or chest wall, supraclavicular fossa and axilla and when directing a boost to the tumour bed. Variations in technique, incorporating immobilisation, treatment energy and dose prescription span the entire radiation treatment process from localisation to planning and subsequent treatment. A range of dose/fraction/time schedules were used for tangential fields, nodal fields and the tumour bed boost. As part of the quality assurance programme for the START Trial this independent review of breast radiotherapy practice has provided a baseline of techniques used by centres prior to participating in the trial. It has also presented a view of the complexity of the issues to enable the design of the next phase of the quality assurance programme. Adherence to the trial protocol will ensure acceptable technique and dosimetry across centres.