Background: Idiopathic pulmonary fibrosis (IPF) is a relentlessly progressive disease with a median survival of approximately 3 years. Measurements of lung volumes and diffusion capacity at rest are generally used to monitor the clinical course of IPF. Due to its high mortality, identification of patients at high risk is crucial for treatment strategies such as lung transplantation. This study was design to determine whether the simple 15-step climbing exercise oximetry test accurately characterizes disease severity and survival in patients with IPF. Methods: The study population consisted of 51 patients with progressive IPF. Findings on the 15-step climbing test, pulmonary function tests, cardiopulmonary exercise test and 6-minute walk distance test were assessed at baseline. Participants were prospectively followed for ≥2 years to determine the relationship between the test parameters and survival. Results: On univariate analysis, there were strong correlations between the 15-stair climbing test parameters and survival. On stepwise linear regression analysis, independent significant predictors of mortality were lowest saturation levels on the 15-step test and the 6-minute walk distance test. Conclusions: The lowest saturation and desaturation areas on the 15-step oximetry test are significantly associated with long-term outcome in patients with IPF. We suggest that the 15-step test be used as a simple and reliable tool to predict severity and prognosis in IPF and to identify candidates for lung transplantation. © 2009 International Society for Heart and Lung Transplantation.