Communicating an unfavourable prognosis while maintaining patient hope represents a critical challenge for healthcare professionals. Duty requires respect for the right to patient autonomy while at the same time not doing harm by causing hopelessness and demoralisation. In some cases, the need for therapeutic privilege is discussed. The primary objectives of this study were to explore HPs’ perceptions of hope in the prognosis communication and investigate how they interpret and operationalise key ethical principles. Sixteen qualitative semistructured interviews with HPs from different positions and experience, including doctors and nurses in four different departments, were conducted in the Ticino Cantonal Hospital, Switzerland. The interviews were recorded, transcribed verbatim and analysed using thematic analysis. HPs defined prognosis and patient hope as interdependent concepts related to future perspectives for subjective quality of life. Two main factors allow HPs to maximise the benefits and minimise the harm of their communication: respecting the patient’s timing and sharing the patient’s wishes. Time is required to reframe needs and expectations. Furthermore, communication needs to be shared by HPs, patients and their relatives to build common awareness and promote a person-centred approach to prognosis. In this process, interprofessional collaboration is key: doctors and nurses are complementary and can together guarantee that patients and relatives receive information in the most appropriate form when they need it. Organisational aspects and the HPs’ emotional difficulties, particularly in coping with their own despair, are barriers to effective communication that need further investigation.