This article illustrates that the diagnostic evaluation as well as the management of the patient presenting with chronic fatigue can be done in an orderly manner. If a medical illness is the cause of the patient's fatigue, this is usually evident on initial presentation. A thorough history and complete physical examination, in conjunction with some screening laboratory tests, can rule out most medical causes of fatigue, and any remaining cases declare themselves over the next several visits. If a medical cause is not evident, a further "fishing expedition" is fruitless. Psychiatric illness, such as depression or generalized anxiety disorder, accounts for another significant proportion of cases of chronic fatigue. As with medical illness, psychiatric illness should be suspected based on history and is not a diagnosis of exclusion. Some patients presenting with chronic fatigue have a history and symptom pattern consistent with the diagnosis of CFS. The cause of this syndrome is controversial and is still unknown. The clinician, however, can offer the patient care in an environment that is respectful of their physical and psychological discomfort and can provide significant symptomatic improvement to the patient. Lastly, some patients with fatigue do not fit any diagnostic category, including CFS. As with many other common complaints, such as headaches or abdominal pain, although a diagnosis may not be given to the patient, the clinician can do a lot to reassure the patient and assist the patient in living with his or her symptoms. As Solberg eloquently wrote: "[E]valuation of the fatigued patient requires all of a physician's best attributes--a broad view of disease, psychosocial sensitivity, and a good ongoing relationship with the patient."