Background: In an earlier paper of the European multi-centre ODIN study (Ayuso-Mateos et al. 2001) we found remarkable urban preponderance in comparison to the corresponding rural site in the female prevalence of depressive disorder in the UK and Ireland. The aim of this paper is to analyse the possible reasons for this finding. Method: A representative sample of 12,702 people aged between 18 and 64 residing in specified urban and rural areas were screened by the Beck Depression Inventory (BDI) for depressive disorder in four European countries (Finland, Ireland, Norway and the UK). Those over cut-off (BDI score < 12) and a 5 % random sample of those under cut-off underwent diagnostic interview including the SCAN version 2.0, and completed a battery of additional research instruments. Results: The estimated 1-month prevalence of depressive disorder according to ICD-10 was 9 % in the total ODIN sample. A large between-country variation was found in female urban prevalence, with Ireland (Dublin) and the UK (Liverpool) having a remarkably high rate. The women in these same countries showed a significant urban/rural difference, whereas in men and in the total sample this difference was non-significant. Logistic regression analysis including some selected risk factors of depression showed still higher risk of depressive disorder both in Dublin and Liverpool compared with the Finnish urban site (Turku), which had the lowest urban prevalence. In addition, also such factors as lack of confidant and having difficulties in getting practical help from neighbours were important predictors of depressive disorder. Similarly, when analysing the different countries separately, the significance of the urban/rural difference in women remained for Ireland and the UK, indicating that the other risk factors studied could not totally explain the difference. Conclusions: ODIN is the first European study on occurrence of depressive disorder in both urban and rural settings allowing closer analysis of the urban/rural differences. The most striking result was the large urban/rural difference in women in the two countries from the British Isles which could not be totally explained by the socio-demographic factors included in this study.