OBJECTIVE: Economically disadvantaged children receive less preventive asthma care and more inpatient care. Studies have not evaluated the association of insurance status on children with severe exacerbations. We evaluated differences in severity of illness, resource use, and outcome associated with Medicaid insurance among children receiving intensive care for asthma. DESIGN: Retrospective cohort study. SETTING: Fourteen American pediatric intensive care units participating in the Pediatric Intensive Care Evaluations database. Methods: Patients with a primary diagnosis of asthma treated from May 1995 to February 2000 were identified. Demographic information and clinical data were evaluated to determine whether there was an association between Medicaid insurance, severity of illness, and length of stay. RESULTS: Twenty-six percent of the children had Medicaid insurance; 22% of children with Medicaid insurance received mechanical ventilation compared with 15% of those with commercial insurance and 16% in a health maintenance organization. After adjustment for severity of illness (Pediatric Risk of Mortality III and use of invasive therapies), Medicaid insurance was significantly associated with increased length of stay in the intensive care unit and hospital. Among children who received mechanical ventilation, patients with Medicaid also received ventilator support significantly longer. CONCLUSIONS: Asthmatic children receiving Medicaid had longer pediatric intensive care unit and hospital stays and an increased risk of mechanical ventilation compared with asthmatic children with commercial or health maintenance organization insurance. Further studies are needed to evaluate differences in outcome and resource utilization for economically disadvantaged asthmatic children.