Previous reports demonstrating quality-of-life impairment in anxiety and affective disorders have relied upon epidemiological samples or relatively small clinical studies. Administration of the same quality-of-life scale, the Quality of Life Enjoyment and Satisfaction Questionnaire, to subjects entering multiple large-scale trials for depression and anxiety disorders allowed us to compare the impact of these disorders on quality of life. Baseline Quality of Life Enjoyment and Satisfaction Questionnaire, demographic, and clinical data from 11 treatment trials, including studies of major depressive disorder, chronic/double depression, dysthymic disorder, panic disorder, obsessive-compulsive disorder (OCD), social phobia, premenstrual dysphoric disorder, and posttraumatic stress disorder (PTSD) were analyzed. The proportion of patients with clinically severe impairment (two or more standard deviations below the community norm) in quality of life varied with different diagnoses: major depressive disorder (63%), chronic/double depression (85%), dysthymic disorder (56%), panic disorder (20%), OCD (26%), social phobia (21%), premenstrual dysphoric disorder (31%), and PTSD (59%). Regression analyses conducted for each disorder suggested that illness-specific symptom scales were significantly associated with baseline quality of life but explained only a small to modest proportion of the variance in Quality of Life Enjoyment and Satisfaction Questionnaire scores. Subjects with affective or anxiety disorders who enter clinical trials have significant quality-of-life impairment, although the degree of dysfunction varies. Diagnostic-specific symptom measures explained only a small proportion of the variance in quality of life, suggesting that an individual's perception of quality of life is an additional factor that should be part of a complete assessment.