Chronic fatigue syndrome (CFS) is characterized by severe fatigue and other non-specific symptoms. It causes disturbance of normal function. Uncertainty about etiology and the appropriate treatment, combined with high prevalence of psychiatric comorbidity, cause a problem in the perception of the disease by the patient, physician and society.This review recapitulates the updated information regarding CFS. It addresses the following aspects: definitions, diagnosis, demographic figures, etiology and treatment options. Since much about CFS is yet to be known, a large amount of work has recently been performed on this subject. Current perceptions, as recognized today, are also presented.A literature search was performed using Medline.Accurate diagnosis of CFS patients is low despite the disabling fatigue. CFS patients present certain demographic characteristics and the illness etiology is as yet unclear. Nonetheless, many possible directions exist with inconclusive evidence about certain suspected causes. There are no treatment guidelines available. Different treatment approaches were investigated without consensus on the results.CFS is an illness that should be taken seriously by the medical establishment. Conscious awareness of the malady might reduce rates of undiagnosed patients. The different etiologic factors showing some degree of involvement in CFS, might suggest that this syndrome is a multi-factorial condition. Despite the fact that there is no distinct undisputed treatment, there are 2 treatments (cognitive behavioral therapy and graded exercise therapy) that might be effective.