Objective: To determine adherence to guidelines for severe asthma care and evaluate regional variability in practice among pediatric intensive care units (PICU). Study design: A retrospective cohort study of children treated for asthma in a PICU during 2000 to 2003. We utilized the Pediatric Health Information System (PHIS) database to identify patients and determine use of asthma therapies when patients did not improve with standard therapy (inhaled β -agonists and systemic corticosteroids). Results: Of 7125 children studied,59% received inhaled anticholinergic medications. Use of other therapies included systemic β -agonists (n = 1841 26% ), magnesium sulfate (n = 1521 21% ), methylxanthines (n = 426 6% ), inhaled heliumoxigen gas mixture (heliox) (n = 740 10% ), and endotracheal intubation with ventilation (n = 1024 14% ). Use of therapies varied by census region. Over half the patients (n = 524) who received ventilation did so for ≤ 1 day. Adjusted for severity of illness, use of mechanical ventilation varied significantly by census division; however, much of the variation was among children ventilated for ≤ 1 day. Conclusion: Adherence to national guidelines for use of inhaled anticholinergics among critically ill children is low, and marked variation in use of invasive ventilation exists. More explicit guidelines regarding indications for invasive ventilation may improve asthma care. Objective: To determine adherence to guidelines for severe asthma care and evaluate regional variability in practice among pediatric intensive care units (PICU). Study design: A retrospective cohort study of children treated for asthma in a PICU during 2000 to 2003. We utilized the Pediatric Health Information System (PHIS) database to identify patients and determine use of asthma therapies when patients did not improve with standard therapy (inhaled β -agonists and systemic corticosteroids). Results: Of 7125 children studied, 59% received inhaled anticholinergic medications. Use of Other therapies included systemic beta -agonists (n = 1841 26%), magnesium sulfate (n = 1521 21%), methylxanthines (n = 426 6%), inhaled heliumoxigen gas mixture Use of therapies varied by census region. Over half the patients (n = 524) who received ventilation did not for so 1 day. Adjusted for severity of illness, use of mechanical ventilation varied significantly by census division; however, much of the variation was among children ventilated for <1 day. Conclusion: Adherence to national guidelines for use of inhaled anticholinergics among critically ill children is low, and marked variation in use of invasive ventilation exists. More explicit guidelines about indications for invasive ventilation may improve asthma care.