OBJECTIVE: To expand the concept of recurrent brief depression (RBD) to brief depression (BD) and to test its clinical relevance. METHOD: Subjects (N = 591) were studied prospectively six times from ages 20/21 to 40/41 years. RBD was defined according to DSM-IV as episodes under 2 weeks with about monthly recurrence and work impairment. BD embraces RBD and brief depressive episodes with a frequency of 1-11 per year. RESULTS: Pure BD and pure major depressive episodes (MDE) did not differ in treatment rates, family history of mood and anxiety disorders or comorbidity with bipolar spectrum and anxiety disorders but they differed in work impairment, suicide attempt rates and distress self-ratings. The combination of BD + MDE identified a very severe group of MDE, comparable with combined depression (MDE + RBD) and double depression (MDE + dysthymia). CONCLUSION: Our data argue for the use of BD as a diagnostic specifier for severe MDE. RBD remains an important independent subgroup.