Objectives: Forecasting survival in cancer is a particularly challenging facet of oncological work and can involve complex interactions with patients and their families. While there is considerable research on patient experiences of being provided with, or becoming aware of, their prognosis, there has been much less emphasis placed on the experiences of caregivers. The aim of this paper was to examine caregivers' experiences of prognosis.; Design: This study used semistructured interviews; transcripts were analysed thematically using the framework approach. These data are part of a larger research project focused on experiences of cancer survivorship.; Setting: Recruitment was from two metropolitan hospitals in Queensland, Australia.; Participants: 50 caregivers of patients living with cancer and receiving treatment at two metropolitan hospitals (32% male, 68% female) participated in this study.; Results: Four main themes were identified: (1) caregivers' uncertainty around the meaning and implications of prognosis, (2) caregivers' sense of exclusion in prognostic conversations, (3) the practice of situating prognosis within a context of hope and (4) the precarious balance between realism, optimism and strategic 'ignorance'.; Conclusions: Caregivers are in many respects the unseen third party of prognostic communication. Developing a better understanding of caregivers' perceptions of prognosis, including how this may be challenged, accepted or otherwise, is important in engaging caregivers in the process of communicating prognostic information. Facilitating greater participation by caregivers in prognostic conversations could potentially address evident complexities and even improve the experiences of all stakeholders in cancer care settings.