Cancer trajectories now follow a jagged path based on multiple probabilities. Thus, uncertainty now typifies cancer caregiving. What impact does uncertainty have on cancer carer grief? This article explores cancer carers' experiences of loss, based on qualitative interviews with 32 Australian carers of a spouse with cancer. Findings suggest that in addition to conventional and anticipatory grief, many carers experience indefinite loss. Indefinite loss characterised the experiences of spouses caregiving outside of the terminal stage. They experienced the current loss of a taken-for-granted certain future, but the future loss of their spouse remained uncertain. They described a heightened awareness of mortality, and an inability to plan for the future. Losses that are uncertain and potential are largely neglected within the grief literature. In this article, I offer the concept indefinite loss and extend health professionals' understanding of cancer carer loss.