Randomised clinical trials have come to be regarded as the gold standard in treatment evaluation. However, many doctors see the discussion of a clinical trial as an intrusion into the doctor–patient relationship and find these discussions difficult to initiate. Detailed informed consent is now a requirement of patient participation in trials; however, it is known that patients commonly fail to understand and recall the information conveyed. These difficulties for doctors and patients raise questions about the ethical integrity of the informed consent process. In this study, we have developed a set of communication strategies underpinned by ethical, linguistic and psychological theory, designed to assist doctors in this difficult task. Initially, audiotape transcripts of 26 consultations in which 10 medical oncologists invited patients to participate in clinical trials were analysed by expert ethicists, linguists, oncologists and psychologists, using rigorous qualitative methodology. A subset of seven of these was subjected to detailed linguistic analysis. A strategies document was developed to address themes which emerged from these analyses. This document was presented to relevant expert stakeholders. Their feedback was incorporated into the final document. Four themes emerged from the analysis; (a) shared decision-making, (b) the sequence of moves in the consultation, (c) the type and clarity of the information provided and (d) disclosure of controversial information and coercion. Detailed strategies were developed to assist doctors to communicate in these areas. We have developed a set of ethical strategies which may assist health professionals in this difficult area. A training package based on these strategies is currently being evaluated in a multi-centre randomised controlled trial.