To improve the clinical measurement of dyspnea, we developed a baseline dyspnea index that rated the severity of dyspnea at a single state and a transition dyspnea index that denoted changes from that baseline. The scores in both indexes depend on ratings for three different categories: functional impairment; magnitude of task, and magnitude of effort. At the baseline state, dyspnea was rated in five grades from 0 (severe) to 4 (unimpaired) for each category. The ratings for each of the three categories were added to form a baseline focal score (range, 0 to 12). At the transition period, changes in dyspnea were rated by seven grades, ranging from -3 (major deterioration), to +3 (major improvement). The ratings for each of the three categories were added to form a transition focal score (range, -9 to +9). In 38 patients tested with respiratory disease, interobserver agreement was highly satisfactory for both indexes. The baseline focal score had the highest correlation (r = 0.60; P less than 0.001) with the 12-minute walking distance (12 MW), while significant, but lower, correlations existed for lung function. For the transition focal score, there was a significant correlation only with the 12 MW (r = 0.33; p = 0.04). These results indicate that dyspnea can receive a direct clinical rating that provides important information not disclosed by customary physiologic tests.