Objective. To assess the diffusion of a quality improvement (QI) programme among allied health professions in The Netherlands. Design. Descriptive study, based on a questionnaire distributed to allied health professionals; response rate, 63%. Settings and participants. All subsectors in health care were covered, including primary care and institutional care. The participants were either salaried or self-employed in private practice. Intervention. The governing boards of the professional associations developed a QI policy. This study reports the evaluation of the diffusion of this policy. Main outcome measure. Respondents' knowledge of the QI programme and their opinions with respect to the relevance of 15 QI activities. Respondents were asked whether they were currently taking part in QI activities and, if not, whether they intended to participate in them in the near future. In addition, the advantages of the QI programme and the barriers to further implementation which respondents perceived were assessed. Results. Most of the health professionals were familiar with the QI programme. The relevance of the QI activities for the profession was rated. Continuing education was ranked highest in priority. The respondents perceived the advantages of many of the QI activities. At the time of the study, less than one-third of the respondents were taking part in peer review, or complying with national guidelines. Respondents listed a number of barriers to further implementation. Conclusions. The perceived advantages and barriers related to implementation appear to differ per QI activity. Consequently, implementation strategies should differ per QI activity and be tailored to the specific advantages and barriers of each one.