To assist patients with chronic obstructive pulmonary disease (COPD) in advance planning for life-threatening exacerbations, we developed a structured decision aid that describes the process, risks, and outcomes of intubation and mechanical ventilation (MV). Thirty-three patients with severe COPD took part in a before-after evaluation study. At baseline, only two participants (6%) reported that they had already made an advance decision about MV. After reviewing the decision aid, 31 participants (94%) reported that they had made a choice, which in 23 cases (74% of those deciding) was to forego MV. These choices were associated with more accurate expectations of MV outcome, and reduced decisional conflict. Qualitatively, participants who would accept MV emphasized their wish to prolong life, whereas those who would forego MV were more influenced by the burdens of treatment and the perception of a poor long-term outcome. However, there was evidence that 24% of participants did not completely comprehend the decision aid and 27% found the experience to be stressful. These findings indicate that a decision aid for MV helps patients plan for life-threatening exacerbations, and may be a useful adjunct to counseling for some patients with severe COPD.