The ideal treatment of infantile spasms is unclear, but many studies advocate hormonal treatment. In the United States, intramuscular ACTH is most widely used, despite the problematic financial cost and side effect profile. Since September 2007, we have replaced ACTH with high-dose oral prednisolone (40-60 mg/day) according to the 2004 United Kingdom Infantile Spasms Study (UKISS). Ten of 15 (67%) infants with new-onset and previously treated infantile spasms became spasm free within 2 weeks; 4 later recurred. More children with an idiopathic etiology for infantile spasms were spasm free than were symptomatic cases (88% vs 43%, P=0.10). Spasm freedom was equivalent to our most recent 15 infants receiving ACTH, with 13 (87%) responding, P=0.16. Oral prednisolone had fewer adverse effects (53% vs 80%, P=0.10) and was less expensive ($200 vs approximately $70,000) than ACTH. We now routinely recommend oral prednisolone to all families of children with infantile spasms.