We retrospectively studied the outcomes of adult patients with cystic fibrosis (CF) hospitalized for severe pulmonary exacerbations (69 cases) between January 1997 and June 2001. Cases were treated either in the Pulmonary Department (n = 46) or in the intensive care unit (ICU) (n = 23) depending on severity. Noninvasive mechanical ventilation was used in 61% (14 of 23) and 33% (15 of 46) of cases treated in the ICU and the Pulmonary Department groups, respectively. Invasive ventilation was necessary in 4 of 23 cases treated in the ICU. The 1-year survival rate was 52% (12 of 23) and 91% (42 of 46) in the ICU and the Pulmonary Department groups, respectively. Lung transplantation was performed in two patients from the ICU group and in five patients from the Pulmonary Department group after hospital discharge. Factors predictive of death were prior colonization with Burkholderia cepacia and rapid decline in FEV1 before admission and severity of exacerbations (severity of hypoxemia and hypercapnia, simplified acute physiology score II and logistic organ dysfunction (LOD) scores, requirement of noninvasive mechanical ventilation, and hospitalization in the ICU) in the univariate analysis and were prior colonization with B. cepacia, the severity of hypoxemia at admission, and hospitalization in the ICU in the multivariate analysis. In 1-year survivors, pulmonary exacerbation did not affect the progression of the disease.