Major criteria:

At least six months' duration; does not resolve with bed rest; reduces daily activity to less than 50 percent; other conditions have been excluded

Physical criteria:

Low-grade fever; nonexudative pharyngitis; lymphadenopathy

Minor criteria:

Sore throat; mild fever or chills; lymph node pain; generalized muscle weakness; myalgia; prolonged fatigue after exercise; new-onset headaches; migratory noninflammatory arthralgia; sleep disturbance; neuropsychological symptoms (e.g., photophobia, scotomata, forgetfulness, irritability, confusion, inability to concentrate, depression, difficulty thinking); description of initial onset as acute or subacute