To find some of the variables associated with values on the Edinburgh Postnatal Depression Scale (EPDS) which suggest postnatal depression in women living in the province of Soria.Population-based case study with controls.Soria Health Region.Women living in Soria giving birth in the INSALUD General Hospital between January and October 2000.Questionnaire sent by mail, containing socio-economic variables, pathology background, gynaecological and obstetric details, the EPDS and the APGAR Family score. Those questionnaires filled in between the third and eighth week after birth were considered valid.340 questionnaires out of 556 sent out were received back (61.2% reply rate). 34 were excluded for lack of data or evident mistakes. 15.7% (95%, CI, 11.6-19.8) of the women scored 13 or more on the EPDS and were at risk of suffering postnatal depression. The independent variables associated with postnatal depression were: age of mother, poor or very poor economic situation, personal history of disturbed states of mind, being anaesthetised during birth and family dysfunction.The risk of postnatal depression was mainly related to socio-economic and family variables. Identification of these variables along with application of the EPDS after giving birth raises the alarm for a possible postnatal depression, and enables the study and follow-up in benefit of the mother and of the subsequent evolution of the new-born to be initiated.