Fatigue is a significant problem in health care. The relationship between chronic fatigue and psychiatric disorders has generated significant interest in recent years. Increased rates of psychiatric disorder among individuals with chronic fatigue have been reported. Fatigue may be defined as physical and/or mental weariness resulting from exertion. The cause of fatigue is complex, influenced by events occurring in both the periphery and the central nervous system. Because fatigue may result from a number of causes, it should be treated comprehensively. The treatment is largely symptomatic and rehabilitative.