Childhood cerebral X-linked adrenoleukodystrophy (X-ALD) is a rare neurodegenerative disease typically presenting from age 4 to 8 years in males. We report 2 cases of X-ALD in boys. The diagnosis of Addison's disease was made before the development of neurological symptoms in both cases. The first patient had hyperpigmentation of the lips and an adrenocorticotropic hormone (ACTH) level higher than 1250 pg/mL when he was 7 years 3 months old. The initial diagnosis was Addison's disease, but X-ALD was diagnosed at age 8 years 8 months, when his motor and mental function deteriorated. The second boy had hypoglycemia, skin pigmentation, and an ACTH level of 1086 pg/mL when he was 4 years 6 months old, but the diagnosis was changed from Addison's disease to X-ALD owing to deterioration in speech at age 7 years. Since both bone marrow transplantation and Lorenzo's oil are beneficial only at the early stage of disease and idiopathic Addison's disease is very rare in children, it is important to test for very-long-chain fatty acids in boys suspected of having Addison's disease.