BACKGROUND: Evidence suggests a role for oestrogen in depression but the involvement of oestrogen receptor polymorphisms remains unknown. AIMS: To determine the association between oestrogen receptor polymorphisms and late-life depression and the modifying effect of hormone treatment. METHOD: Depression was assessed using the Mini-International Neuropsychiatric Interview, according to DSM-IV criteria and the Centre for Epidemiologic Studies - Depression Scale. The association between oestrogen receptor α and β (ER-α and ER-β) polymorphisms with severe depression was examined in 6017 community-dwelling elderly people using multivariate logistic regression. RESULTS: In women, the ER-α rs2234693 and rs9340799 polymorphisms were significantly associated with the risk of late-life depression. The A allele of ER-β rs1256049 increased the risk of depression, but only for non-current users of hormone treatment. In men, only the ER-β rs4986938 polymorphism showed a weak association with depression risk. CONCLUSIONS: Oestrogen receptor polymorphisms are associated with severe late-life depression risk in women only.