A new clinical index of dyspnea and fatigue has been applied to rate the condition of patients with congestive heart failure. The index has 3 components, each rated on a scale from 0 to 4, for the magnitude of the task that evokes dyspnea or fatigue, the magnitude of the pace (or effort) with which the task is performed and the associated functional impairment in general activities. The ratings for each component are added to form an aggregated score, which can range from 0, for the worst condition, to 12, for the best. Because dyspnea and fatigue are prime symptoms and sources of clinical distress, the index helps reflect the quality of life in patients with congestive heart failure. In double-blind trials of therapy, changes in the index showed good correlations with patients' self-selected ratings of improvement. The posttherapeutic changes in the index ratings were significantly higher with a new active agent (lisinopril) than with placebo or another active agent (captopril).