OBJECTIVES: To compare prescription patterns and treatment adherence to inhaled corticosteroids (ICS) and leukotriene-receptor antagonists (LTRA) among asthmatic children. METHODS: Using the Quebec ( Canada) administrative health databases, we identified a cohort of 27,355 asthmatic children aged 5 to 15 years in whom monotherapy with ICS or LTRA was initiated between January 1, 1998 and August 31, 2005. Prescription patterns were examined by the proportion of days’ supply prescribed (PDSP: number of days with supply prescribed from all physicians a patient consulted over the number of days of follow-up). Adherence to therapy was estimated by the proportion of prescribed days covered (PPDC: number of days’ supply dispensed over the number of days’ supply prescribed during the follow-up). The mean PDSP and PPDC were compared between ICS and LTRA patients using t-tests. All analyses were stratified by the presence or the absence of an asthma exacerbation in the year prior to treatment initiation with ICS or LTRA. RESULTS: Among patients who had an asthma exacerbation, 7427 initiated ICS and 67 initiated LTRA therapy. Corresponding figures were 19439 and 422 among patients who did not have an asthma exacerbation. The mean PPDC was similar between ICS and LTRA users in both strata (68.0 % vs 64.7% in the exacerbation stratum and 63.9 vs 62.7 in the no exacerbation stratum), but the PDSP was significantly lower among ICS users (32.8% vs 55.9% (p-value <0.001) in the exacerbation stratum and 34.0% vs 51.9% (p-value <0.001) in the no exacerbation stratum). CONCLUSIONS: Asthmatic children treated with ICS and LTRA had similar treatment adherence to the prescribed medications, but ICS appeared to be more frequently prescribed as an intermittent rather than a daily controller therapy, resulting in lower usage of ICS.