Objective: To examine the effect of pirfenidone on the survival of patients hospitalized due to acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF). Methods: The outcomes of 11 consecutive AE-IPF patients who were receiving pirfenidone treatment when they were admitted to a respiratory intensive care unit (RICU) for acute respiratory failure (ARF) (treatment group) were retrospectively compared with those of 9 patients who were not on pirfenidone treatment at admission (control group). The study's primary outcome measure was survival following RICU admission; the patients' mortality rate and the length of time spent in the RICU were also assessed. Results: The treatment group had significantly longer survival than the control group (median survival time: 137.0 [95% CI, 39.0-373.0] versus 16.0 [95% CI, 14.0-22.0] days; p = .0009); the hazard ratio for death was 0.2896 (95% CI, 0.09541-0.8791). The treatment group also tended to have a lower RICU mortality rate (3/11 vs. 7/9; p = .0698). Conclusions: Pirfenidone significantly improved survival in IPF patients hospitalized for severe acute exacerbation compared to controls.