The study described in this article addressed the phenomena of living with a diagnosis of colorectal cancer. Rationale for undertaking the research was that a need had been identified to describe the experience of living with a diagnosis of colorectal cancer and what this means to an individual. To explore the lived experience of colorectal cancer, a phenomenological study was undertaken based on Heidegger's philosophy as presented in his seminal work 'Being and Time'. Seven patients diagnosed with colorectal cancer were interviewed over a time-span of 13 months. Patients participating in the study were recruited from three Swiss hospitals. Data were analysed by following Colaizzi's eight-step process as cited in Haase (1987, p 66-67). Analysis identified one main category: 'The Omnipresence of Cancer' and two sub-categories: 'Towards Authentic Dasein' (Towards Authentic Being) and 'Mapping out the Future'. The research demonstrated that having received a diagnosis of cancer means an individual is faced with the potential of lifelong illness and death, feels stigmatised by the diagnosis and is classified as belonging to an illness group. Individuals who have been diagnosed with colorectal cancer need to talk with health-care professionals about their experiences and concerns. It is important that in-depth discussions occur between patients and health-care professionals so that the patient's questions and uncertainties may be addressed.