[Chronic fatigue--'tired with 23 i's'].

Two patients, a woman aged 32 years and a man aged 49, presented with severe chronic fatigue. The woman had chronic fatigue syndrome; she recovered slowly. The man suffered from a pituitary adenoma producing follicle stimulating hormone; he recovered after transsphenoidal hypophysectomy. In patients with chronic fatigue, the history and a thorough physical examination to exclude underlying illness are very important; secondary symptom criteria must not be overemphasized (as is the case with the Holmes and Fukuda criteria), chronic fatigue syndrome should not be diagnosed if the condition has a shorter duration than 6 months, but it should be diagnosed if the clinical picture is compatible. The prognosis is not poor: in patients with a median disease duration of 4.5 years, 20% show significant improvement over an 18-month period.