BACKGROUND: Asthma in childhood has a significant impact on children and families, in part because of the frequent need for hospital-based care for acute exacerbations. Sensitization and exposure to inhalant allergens have been identified as risk factors for asthma hospitalization. OBJECTIVE: The Childhood Asthma Management Program (CAMP), comprised of 1041 children aged 5 to 12 with mild-to-moderate asthma, provides the opportunity to identify specific risk factors for prior hospitalization for asthma. METHODS: Data gathered during the screening period from CAMP were evaluated to elucidate differences between patients who had ever been hospitalized for asthma before enrollment in CAMP and those who had never been hospitalized. RESULTS: Univariate analyses indicated that prior hospitalization for asthma was associated with a younger age of asthma onset, longer duration of asthma, greater number of positive allergy skin tests, higher serum immunoglobulin E level, greater peripheral blood eosinophilia, greater recent inhaled corticosteroid use, greater airflow obstruction, greater airway hyperresponsiveness, and lower patient intelligence quotient (IQ). Gender, race, and family income did not differ between hospitalized and never-hospitalized patients. The combination of both sensitization and exposure to high levels of dog allergen (Can f1) was associated with greater likelihood of prior hospitalization. Forward multivariate logistic regression analysis identified younger age of asthma onset, longer duration of asthma, recent use of asthma controller therapy, greater airflow obstruction, and lower patient IQ as significant risk factors for prior hospitalization when all risk factors identified by univariate analysis were included in the model. CONCLUSIONS: Children with mild-to-moderate asthma who had a past hospitalization for acute asthma had greater asthma severity, younger age of onset, and lower patient IQ at the time of entry into CAMP. They also had more markers of atopy than children without prior hospitalization, although atopy was not associated with prior hospitalization on multivariate analysis. Although we have identified these risk factors in a retrospective manner, one can speculate that the persistence of these features should alert the clinician to closely follow abnormalities on pulmonary function tests and general features of atopy to potentially identify patients at risk for future hospitalization.