The aim of the present study was to estimate depressive disorder and symptomatology prevalence and incidence in perinatal period in a population-based sample. Three-hundred and eighty six Portuguese women (mean age=30.08 years, SD=4.21) were interviewed with the Diagnostic Interview for Genetic Studies and completed Beck Depression Inventory-II/BDI-II and Postpartum Depression Screening Scale/PDSS, in pregnancy and postpartum. OPCRIT polydiagnostic system generated ICD-10 and DSM-IV diagnoses. One-month prevalence in pregnancy was of 2.3%/ICD-10 and 1.3%/DSM-IV; in postpartum it was of 16.6% and 11.7%. Pregnancy incidence was of 0%/ICD-10 and .3%/DSM-IV and in postpartum of 7.5%/ ICD-10 and 4.9%/DSM-IV. Depression pregnancy point-prevalence found with BDI-II cutoffs ranged from 13.7% to 19.4% in pregnancy and from .8% to 13.0% in postpartum and with PDSS from 14.2% to 17.9% in pregnancy and from 3.9% to 12.7% in postpartum. In the same sample, different diagnostic systems generated different prevalence and incidence rates. Higher prevalence rates were found using self-reported questionnaires. ICD-10 generated higher prevalence and incidence rates than DSM-IV.