X-linked adrenoleukodystrophy is a neurodegenerative disorder affecting the myelin of the nervous system and the adrenal cortex. The childhood form of the disease is typically heralded by subtle neurocognitive changes which later progress. Acute presentation of childhood ALD has been reported, but the incidence is not known. We reviewed the records of 485 boys with childhood ALD, determined those with acute presentation, and classified them as adrenal crisis, seizures, or encephalopathy. Of the 485 reviewed cases, 45 (9.3%) presented acutely at an average age of 5.5 years. Twenty of 45 (44%) presented with seizures, focal seizures in 6 boys and generalized in the remainder with 4 having status epilepticus. Twenty out of 45 presented with acute adrenal crisis. Five of 45 presented with acute encephalopathy or coma. The diagnosis of ALD was rarely made in the acute period, but was often suggested by neuroimaging. The accurate, rapid diagnosis of ALD has important implications for treatment as well as for other family members and should be considered in appropriate patients.