Background: Various studies support the notion that early onset depression and late onset depression have different etiological pathways. Late onset depression has been found to be a heterogeneous group. This study attempts to divide the late onset group in two subgroups with different aetiology and find evidence for the vascular depression hypothesis. Methods: Subjects were 132 depressed elderly persons from the general population, general practitioners and mental health care outpatient clinics. Sixty-four had early-onset depression ( <60). 69 had late-onset depression ( greater than or equal to 60). The latter group was divided into subjects with (n = 15) and without (n = 15) severe life stress. The groups were compared with respect to a variety of variables including vascular risk factors Results: Early-onset depression was associated with neuroticism and parental history. Subjects with late-onset depression and no severe life stress had higher vascular risk factors than whose depression was preceded by: a severe stressor did. Conclusions: Our findings suggest that late life depression can be divided into subgroups with different etiological pathways: (1) early-onset with longstanding psychobiological vulnerability: (2) late-onset as reaction to severe life stress; and (3) late-onset with vascular risk factors. (C) 2001 Elsevier Science B.V. All rights reserved.