There is growing recognition that patients should have greater opportunity to plan their future care, a process known as advance care planning. The aims of this phase I qualitative focus group study were (1) to explore the acceptability of an interview schedule, designed to encourage conversations regarding future care; and (2) to explore the suitability of such discussions and inquire about their possible timing, nature and impact. Purposive sampling was used to achieve a balanced sample of 22 palliative care and oncology patients, relatives and user group members. The results showed that, although some patients welcome the opportunity to discuss end-of-life care, others may not feel ready or able to do so. The timing of a discussion is likely to influence its acceptability and effect. A discussion might best be initiated after recurrence of disease. The person initiating discussion should be skilled in responding to the cues of the patient, and should enable the patient to close the topic down at the end of the discussion, in order to avoid dwelling too much on the end of life. Advance care planning should take place over a number of meetings, and be conducted by an appropriately trained professional with sufficient time to talk through the issues raised, and with the knowledge and skills to answer questions, tailor the discussion to the individual, and avoid destroying hope. Advance decisions to refuse treatment should not be the focus of the discussion, but one component of a broader conversation about end-of-life issues. If patients make an advance decision to refuse certain treatments, they should be given the opportunity to change their minds in the future.