Dengue encephalopathy or dengue hemorrhagic fever (DHF) with CNS involvement used to be considered a relatively rare condition; but the number of cases reported in human studies has been increasing every year. Diagnosis of dengue encephalopathy is based on clinically diagnosed DHF according to the W.H.O. criteria (1980), with CNS manifestations consisting of abrupt onset of hyperpyrexia, non-transient alteration of consciousness, headache, vomiting--with or without seizures--and normal CSF. Many factors may be considered to be directly or indirectly associated with CNS signs and symptoms in DHF, the main pathology being leakage of plasma into serous spaces and abnormal hemostasis, leading to hypovolemic shock and hemorrhage in many organs of the body. Acute liver failure is considered to be one of the main factors causing brain pathology. One hundred fifty-two cases of dengue encephalopathy admitted during 3 periods at the Cipto Mangunkusumo Hospital in Jakarta were studied retrospectively. The overall incidence was 152 out of 2,441 DHF cases, or 6.2%. The most pronounced symptoms were hyperpyrexia, alteration of consciousness and convulsions. Laboratory examination showed an unusually high increase of serum transaminases, hyponatremia, and hypoxia. Neurologic abnormalities detected were hemiparesis and tetraparesis of the extremities, and second nerve atrophy; such abnormalities were found in 10 out of the 152 cases, or 6.5%.