Chédiak-Higashi syndrome (CHS) is often a fatal disease of childhood characterized by oculocutaneous forms of albinism with congenital gigantism of peroxidase granules, granulation anomaly of leukocytes, hereditary gigantism of cytoplasmic organelles and a marked susceptibility to infections. A few patients have survived to age 20 years. A 39-year-old woman developed tremor and gait disturbance at age 22 years. At age 25 years, she was admitted to the Hospital for evaluation. Mental impairment, horizontal nystagmus, bradyphrenia, cogwheel rigidity, tremor at tongue, mandible and hands, bradykinesia, and unsteady gait were found and a juvenile parkinsonism was diagnosed. However, there was no favorable response by levodopa therapy. She became unable to walk at age 33 years. On admission, Oct. 27, 1988, at age 39 years, she was bedridden with a posture of decorticate rigidity. She was found to have partial depigmentation of the retina and choroid, pale and atrophic optic disc and subluxation of the mandible, Onuaguluchi's finger deformities and pes cavus. Neurological examination disclosed that she was alert but had marked difficulty in speaking. The communication was only possible by giving a sign of grasping of the left hand. The patient also showed oculogyric crisis, dystonic rigidity of the neck, diffuse muscular atrophy, complete paraplegia and decreased deep tendon reflexes with Babinski sign. On laboratory studies, at age 39, the white cells count was decreased (2,510/mm3), the hemoglobin level was 10.3 g/dl, the serum iron was 12 micrograms/dl, IgG 2,828 mg/dl, IgA 1,002 mg/dl, and the activity of natural killer cell was profoundly decreased (2%, normal; 18-40). Hematological examination revealed peroxidase positive giant granules in leukocytes. Chest X-ray film disclosed marked abnormal colon gas which located right subdiaphragma (Chilaiditi syndrome). Cerebrospinal fluid contained 12 cells/mm3, 99% lymphocytes; protein, 58.8 mg/dl; IgG, 6.8 mg/dl; HVA, 4.5 ng/ml (normal 41.8-44.6); 5-HIAA, 1.3 ng/ml (11.3-29.2); MHPG, 5.8 ng/ml (13.2-22.2).(ABSTRACT TRUNCATED AT 250 WORDS)