This is a retrospective case series reporting lactic acidosis in four pediatric patients with acute severe asthma treated with nebulized beta2-agonists in a pediatric intensive care unit of a tertiary care teaching facility. During treatment with beta2-agonists, these patients developed lactic acidosis with a peak concentration of 5.2 to 13 mmol/l. Lactic acidosis improved within 24 h after discontinuation or decrease in the dosage of beta2-agonists. We conclude that the intensive use of beta2-agonists for acute severe asthma in children may be the primary and significant cause of lactic acidosis.