BACKGROUND: Two British cohort studies have reported birth weight to be associated with self-reported depression in adulthood, even after adjustment for socio-economic factors. AIMS: To examine the relationship between birth dimensions and discharge from a psychiatric ward with a depression diagnosis in adulthood. METHOD: A cohort of 10 753 male singletons born in Copenhagen, Denmark in 1953 and for whom birth certificates had been traced in 1965 were followed from 1969 until 2002, with record linkage for date of first admission to a psychiatric ward that led to a discharge diagnosis of depression. RESULTS: A total of 190 men, corresponding to 1.8% of the cohort, had a discharge diagnosis of depression. The Cox's regression analyses failed to show any association between birth dimensions (birth weight and ponderal index) and risk of psychiatric ward diagnosis of depression in adult life, before or after adjustment for social indicators at birth. CONCLUSIONS: This study does not support the existence of a relation between birth dimensions and psychiatric ward admission for depression in adult men.