Fatigue is frequently experienced by patients with chronic illnesses, and especially by patients with cancer and chronic obstructive airways disease. However, there is a paucity of qualitative research into the experiences of fatigued individuals and, consequently, definitions of fatigue have, to date, been based solely on observation and conjecture. The purpose of this study was to capture a detailed description of the fatigue experienced by individuals with cancer and chronic obstructive airways disease. A phenomenological research design was adopted. The findings presented in this paper depict fatigue as a complex phenomenon. The paper describes the physical and mental sensations embodied in fatigue, the impact of fatigue on everyday functioning, the emotional feelings evoked by fatigue and the impact of fatigue on perceived control. These findings have relevance for clinical nursing and future research.