The current study assessed how negative and positive stress is related to dyspnea perception. The participants were 25 young women with a medical diagnosis of severe asthma, and 15 matched controls. Stress was induced during repeated rollercoaster rides. Results showed that negative emotional stress and blood pressure peaked just before, and positive emotional stress and heart beat peaked immediately after rollercoaster rides. Dyspnea in women with asthma was higher just before than immediately after rollercoaster rides, even in women with asthma with a rollercoaster-evoked reduction in lung function. These results suggest that stressed and highly aroused individuals with chronic asthma tend to perceive dyspnea in terms of acquired, familiar associations between dyspnea and positive versus negative feeling states, favoring either underperception or overperception of dyspnea, depending on the emotional valence of a situation.