High rates of asthma treatment nonadherence have been reported, particularly in economically disadvantaged African American youth. The relationship between adherence to combined medication treatment and asthma outcomes has potential clinical significance but is not well understood. Using electronic monitoring, we describe the pattern of adherence to daily corticosteroid (fluticasone) and leukotriene receptor antagonist (montelukast) medication over the course of 1 year in a population of African American youth with moderate to severe asthma. On average, adherence to montelukast was higher than adherence to fluticasone (p < 0.01); however, for both medications, adherence rates significantly declined over the course of the study. After 1 year, participants took only 31% of prescribed doses of montelukast and 23% of prescribed doses of fluticasone. The decline in adherence to both fluticasone (p < 0.05) and montelukast (p < 0.001) was related to increased healthcare utilization. Furthermore, asthma symptom ratings were related montelukast (p < 0.001), but not fluticasone adherence. These results suggest that adherence promotion intervention strategies are warranted to improve health-related outcomes in families who are at-risk for treatment nonadherence.