Introduction: Hypotension is known to severely impact the prognosis of patients in need of acute care. Endotracheal intubation (EI) is a procedure that is often used in the emergency room for patients with severe conditions. Post-intubation hypotension (PHI) is a well-known adverse effect of EI, although the impact of PHI on mortality is still unclear. The objective of this study was therefore to evaluate the association between post-intubation hypotension (PIH) and in-hospital mortality rates and length of stay (LOS). Methods: Design: A historical cohort of patients admitted in a university-affiliated emergency department (ED) between 06/2011 and 05/2016 was constituted. Population: Patients aged ≥16 were included if pre-EI vital signs were available, if their intubation was performed in the resuscitation room, if no surgical access was needed and if EI was performed in ≤3 attempts. Measures: All clinical data including vitals were prospectively recorded using the software ReaScribe. Hypotension was defined as a systolic blood pressure ≤90 mmHg. The occurrence of PIH was assessed at 5, 15, 30 minutes and any time after intubation. Main outcomes were in-hospital mortality and hospital length of stay. Analyses: Univariate and multivariate analyses assessed the relation between PHI and outcomes. Results: A total of 497 patients were included in our analyses. Of these patients, 63 (12.7%) suffered from PIH at 5 minutes, 120 (24,1%) at 15 minutes, 168 (33,8%) at 30 minutes and 209 (42%) at any moment after intubation. Mortality rates were 42.9% (n = 27), 35.8% (n = 43), 33.9% (n = 57) and 30.6%(n = 64) for patients who presented PIH at the 4 time periods, respectively, while 26.74% patients died in the normotensive group. PIH at 5 (p = 0.006), 15 (p = 0.04) and 30 minutes (p = 0.05) was associated with a significant increase in overall post-intubation mortality. Mean LOS for patients who suffered from PIH was 16.7, 18.9, 17.3, 17.4 days compared to 19.5 (p = 0.22) days for the normotensive group. Conclusion: Early post-intubation hypotension at 5 minutes was strongly associated with an increased mortality. As for the in-hospital length of stay, PIH was not associated with an increased LOS. Our results show that PIH within 30 minutes of intubation is associated with an increased mortality rate and should therefore be aggressively treated or prevented.