Aims. Cancer-related fatigue (CRF) is widely acknowledged as one of the most common and distressing side-effects of cancer and treatment in the academic literature. However, this discourse of CRF is not mirrored in the wider social context or in clinical practice where it is most meaningful to patients. The aim of this study was to construct an understanding of CRF based on the lived experiences of patients who suffer from fatigue related to cancer. Specifically, the factors that help to explain and sustain the absence of a discourse of CRF were explored. Method. Thematic discourse analysis was used to analyse ‘additional comments’ left by 73 fatigued cancer patients and survivors (80% of whom were women) at the end of a questionnaire on CRF. Participants were recruited through cancer associations and support groups in Ireland and the United Kingdom. A constructionist approach, informed by Foucauldian discourse analysis, was used to identify latent themes. Results. The findings supported the absence of a discourse of CRF. Two explanatory themes were identified: (1) a discourse of CRF is hindered because it falls outside the illness process; CRF is at odds with the schema of being a cancer survivor and it fails to fit into the established discourse of falling ill, and (2) a discourse of CRF is actively obstructed because the enormity of cancer works to invalidate and overshadow patients’ post-cancer experiences and uses up patients’ ‘illness quota’. Conclusion. The findings suggest that beyond the lack of recognition, support, and interventions available for patients with CRF, broader discourses of health, illness and cancer are hampering communication regarding this side-effect. Alternative ways in which CRF might be handled in clinical practice, that reduce unnecessary distress and help to validate patients’ experiences while recognising the many potential contributing factors to fatigue in cancer survivors, are considered.