An interactive multimedia computer game to enhance self-management skills and thereby improve asthma outcomes in inner city children with asthma was evaluated. Subjects aged 6-17 were recruited from four pediatric practices and randomly assigned to the computer intervention condition or to the usual-care comparison. The main character in the game could match the subject on gender and ethnicity. Characteristics of the protagonist's asthma were tailored to be like those of the subject. Subjects played the computer game as part of regular asthma visits. Time between pre- and post-test varied from 4 to 15.6 months (mean, 7.6 months). Analysis of covariance, with pre-test scores, age, and asthma severity as covariates, found that the intervention was associated with fewer hospitalizations, better symptom scores, increased functional status, greater knowledge of asthma management, and better child self-management behavior for those in the intervention condition. Interactions with covariates were found and discussed in terms of variable efficacy of the intervention.