Introduction: In Canada, acute asthma is a common cause of emergency department (ED) attendance and its treatment is affected by ED overcrowding and increasing wait times. Literature suggests that a clinical pathway (CP) for the treatment of acute asthma can increase the use of medical therapy, reduce hospital admission rates and decrease associated costs. However, only few have looked at the effect on ED length of stay (ED LOS) when such a CP is initiated by triage nurse/respiratory therapist among adults. In this optic, an asthma CP was launched on Feb. 2016 at Centre Hospitalier Universitaire de Sherbrooke (QC) and included medical directives allowing triage nurse and respiratory therapist initiation of treatment. Methods: The objectives are to determine the effect of an ED nurse/respiratory therapist-initiated asthma CP on (1) ED LOS, (2) time-to-treatment (beta-agonist, corticosteroids), time-to-MD and other secondary outcomes. This was a retrospective before-after study. Adults presenting to the ED before and after CP implementation with a final diagnosis of asthma or asthma exacerbation were eligible. The groups A (before implementation) and B (after implementation) were compared for ED LOS. Three subgroups of 50 patients were generated and compared for outcomes: A1 (before implementation), B1 (after implementation without CP) and B2 (after implementation with CP). All five groups were controlled for triage level and sex. Results: In total, 1086 patients were included; 543 before implementation (Mar. 2011 – Feb. 2016) and 543 after (Feb. 2016 – Jun. 2019), of whom 14% (N = 77) were treated by CP. The average ED LOS was similar (10.36h vs 10.65h; (p = 0,31)) in group A and in group B. In groups A1, B1 and B2, the median ED LOS were respectively 6.00, 6.84, 4.80; these differences were not statistically significant. The average time-to-treatment for beta-agonist in A1, B1 and B2 was respectively 148, 180 and 50 mins; the differences between B2 and A1 and between B2 and B1 were both statistically significant (p < 0,05). Conclusion: Although this study indicates a low compliance to the CP, it shows that time-to-treatment can be reduced. It didn't demonstrate any statistically significant decrease in ED LOS, most likely due to low number of patients and non-normal distribution, but the 1.2h shorter could be a major advantage if it proves true. Further studies are essential to understand facilitators and alleviate the barriers in anticipation of a multi-centric implementation.