Subjects from a family study who had panic disorder and generalized anxiety disorder were compared on the pattern of their symptoms, age and type of onset, personality characteristics, course of illness, and outcome. Subjects with generalized anxiety disorder were shown to have fewer autonomic symptoms and an earlier, more gradual onset. Their illness was also observed to have a more chronic course and a more favorable outcome, although these differences were not statistically significant. The validity of generalized anxiety disorder and panic disorder as discrete diagnostic entities is supported.