Background: Bilevel positive airway pressure (BiPAP) is a form of non-invasive ventilation (NIV) that is used to help and facilitate breathing. Our objective is to evaluate the impact of BiPAP application time on the length of emergency room (ER) stay in pulmonary edema patients. Method: This is a retrospective cohort study that included patients who presented to the ER at King Abdullah Medical City (KAMC) from June 2019 to June 2021. The eligibility criteria for BiPAP application were congestive heart failure (CHF) and type 1 and type 2 respiratory failure, The data were collected from the Track Care system. We defined early BiPAP as BiPAP application time within one hour from admission, and late BiPAP more than one hour and we calculated the percentage of discharge within four hours in each group. Result: Out of 147 fulfilling study eligibility, 64% had CHF, 23% had type 2 respiratory failure and 13% had type 1 respiratory failure. For patients discharged within four hours, 85% were in the early BiPAP and 15% were in the late BiPAP groups (p = 0.001 as compared to the late discharge group). Discharge within four hours was observed with the following percentages in the study subgroups: CHF early BiPAP (84%), late BiPAP (16%) (p = 0.004), type 1 respiratory failure early BiPAP (79%), late BiPAP (21%) (p = 0.71) and type 2 respiratory failure early BiPAP (94%), late BiPAP (6%) (p = 0.89). Conclusion: Our results show that there is a significant outcome in early BiPAP application in decreasing the length of ER stay only in patients with pulmonary edema.