Asthma causes pediatric morbidity throughout the US with substantial regional variability. Emergency department (ED) utilization data were studied to determine if geographic variability of pediatric asthma cases exists within a state. Records for non-neonatal Maryland children less than 18 years of age seen and discharged from Maryland EDs from April 1997 through March 2001 were analyzed. While Baltimore City had the highest rates of asthma visits, adjusted odds ratios identified the wealthiest suburban county to have a higher risk of an asthma ED visit. Children from rural counties, for the most part, had fewer ED asthma visits than children from urban and suburban counties.