BACKGROUND: Understanding the severity of patients' dyspnea is critical to avoid under- or overtreatment of patients with acute cardiopulmonary conditions. OBJECTIVE: To evaluate the agreement between dyspnea assessment by patients and healthcare providers and to explore which factors contribute to discordance in assessment. DESIGN, SETTINGS AND PARTICIPANTS: Prospective study of patients hospitalized for acute cardiopulmonary diseases at an urban teaching hospital. INTERVENTION AND MEASUREMENTS: A numerical rating scale (0-10) was used to assess dyspnea severity as perceived by patients and assessed by providers. Agreement was defined as a score within +/-1 between patient and healthcare provider; differences of > /=2 points were considered over- or underestimations. The relationship between patient self-perceived dyspnea severity and provider rating was assessed using a weighted kappa coefficient. RESULTS: Of the 138 patients enrolled, 33% had a diagnosis of heart failure, 30% chronic obstructive pulmonary disease, and 13% pneumonia; median age was 72 years, and 57% were women. In all, 96 patient-physician and 138 patient-nurses pairs were included in the study. The kappa coefficient for agreement was 0.11 (95% confidence interval [CI]: 0.01 to 0.21) between patients and physicians and 0.18 (95% CI: 0.12 to 0.24) between patients and nurses. Physicians underestimated patients' dyspnea 37.9% of the time and overestimated it 25.8% of the time, whereas nurses underestimated it 43.5% of the time and overestimated it 12.4% of the time. Admitting diagnosis was the only patient factor associated with discordance. CONCLUSIONS: Agreement between patient perception of dyspnea and healthcare providers' assessment is low. Future studies should prospectively test whether routine assessment of dyspnea results in better patient outcomes.