In a longitudinal study of 30 successfully treated unipolar depressed patients, the authors evaluated number of depressive episodes, early onset of depression, and lifetime prevalence of affective disorders other than major depression as risk factors for recurrence. Early onset of depression (before age 20) and a history of affective disorders other than major depression were each significantly associated with recurrence. Number of episodes was not as powerful in predicting recurrence as either early onset or lifetime prevalence of other affective disorders.