Thirty-nine chronic asthmatic children were enrolled in a 6-month outpatient theophylline compliance study. Seventy-two percent of these patients maintained mean theophylline levels greater than or equal to 5 mcg/ml, the definition of theophylline compliance. Both compliant and noncompliant patients showed significant reduction in wheezing symptoms (P less than .005). Demographic factors including age, race, sex, and number of parents at home were not correlated with drug compliance behavior. Specific behavioral interventions were implemented to promote drug compliance. Behavioral interventions that were most effective in achieving compliance were parental encouragement and increasing parental supervision of medication (compliance, asthma, theophylline, behavioral intervention).