Urban minority children have higher rates of asthma morbidity due to multiple factors. Many school-based programs have been funded to improve asthma management, especially for these "high-risk" inner-city children with asthma. Here they report the outcomes of the Children's Hospital of Orange County Breathmobile program, which is a school-based asthma program that combines the use of a mobile clinic and a pediatric asthma specialist. Baseline evaluations included a detailed history and physical, skin prick test to common allergens, spirometry measurements, and asthma severity classification based on the current National Asthma Education and Prevention Program guidelines. From April 2002 to September 2005, a total of 1321 children were evaluated for asthma. Analysis of the 1112 (84%) children diagnosed with asthma showed a population mean age of 7.8 years, 81% Latino ethnicity, and 73% with persistent disease. At baseline, only 24% of children with persistent asthma were on daily anti-inflammatory medications, which increased to 78% by the first follow-up visit. In the year prior to entry into the program, 64% had school absenteeism related to asthma (38% greater than 10 days), 45% had emergency room (ER) visits (28% greater than 1), and 19% had hospitalizations (9% greater than 1). There was a significant reduction (p less than 0.001) in the annual rates of ER visits, hospitalizations, and school absenteeism when comparing pre-and post-entry into the program. These data suggest that a mobile asthma van clinic at the school site with an asthma specialist could be an effective model in reducing morbidity in the underserved child with asthma. Further studies are necessary to determine whether this model is applicable to other inner-city settings.