Objectives Late-life depression often has a chronic course, with debilitating effects on functioning and quality of life; there is still no consensus on important risk factors explaining this chronicity. Cross-sectional studies have shown that childhood abuse is associated with late-life depression, and in longitudinal studies with chronicity of depression in younger adults. We aim to investigate the impact of childhood abuse on the course of late-life depression. Design Two-year longitudinal cohort study. Setting Data were derived from the Netherlands Study of Depression in Older Persons (NESDO). Participants 282 participants with a depression diagnosis in the previous 6 months (mean age: 70.6 years), of whom 152 (53.9%) experienced childhood abuse. Measurements Presence of childhood abuse (yes/no) and a frequency-based childhood abuse index (CAI) were calculated. Dependent variable was depression diagnosis after 2 years. Results Multivariable mediation analysis showed an association between childhood abuse and depression diagnosis at follow-up. Depression severity, age at onset, neuroticism, and number of chronic diseases were important mediating variables of this association, which then lost statistical significance. For childhood abuse (yes/no), loneliness was an additional, significant mediator. Depression severity was the main mediating variable, reducing the direct effect by 26.5% to 33.3% depending on the definition of abuse (respectively, ‘yes/no” abuse and CAI). Conclusions More depressive symptoms at baseline, lower age at depression onset, higher levels of neuroticism and loneliness, and more chronic diseases explain a poor course of depression in older adults who reported childhood abuse. When treating late-life depression it is important to detect childhood abuse and consider these mediating variables.