Background: Due to the high prevalence of depression, it is clinically relevant to improve the early identification and assessment of depressive episodes. The main objective of the present study was to examine the psychometric properties of the IDS-SR30 (Self-rated Inventory of Depressive Symptomatology) in a large Spanish sample of depressive patients. Methods. This prospective, naturalistic, multicenter, nationwide epidemiological study conducted in Spain included 1595 adult patients (65.3% females) with a DSM-IV Major Depressive Disorder (MDD. IDS-SR30 and the Hamilton Depression Rating Scale (HDRS, 21 items)were administered to the sample. Data was collected during 2 routine visits. The second assessment was carried out after 10 2 weeks after first assessment. Results: The IDS-SR30 showed good internal consistency ( = 0.94) and high item total correlations ( 0.50) were found in 70% of the items. The convergent validity was 0.85. Results of the principal component analysis (PCA) and confirmatory factor analyses (CFA) showed that a three factor model (labelled mood/cognition, anxiety/somatic and sleep) is adequate for the current sample. Conclusions: The Spanish version of the IDS-SR30 seems a reliable, valid and useful tool for measuring depression symptomatology in Spanish population.