This prospective study aimed to assess the suitability of the 21-item Beck Depression Inventory (BDI-21) as a screening method for current episodes of major depressive disorder in different phases of the disease. In a sample of treatment-seeking outpatients (n=125), a structured interview method (SCID) was used twice with a 2-year interval to screen whether the patient had a current episode of major depressive disorder. The validity of the BDI-21 was also analysed by means of receiver operating characteristic (ROC) curves. The results showed that with a cut-off point of 14/15 the BDI-21 can be used to indicate the presence of a major depressive episode regardless of the phase of the major depressive disorder. The sensitivity and specificity were quite satisfactory with this cut-off point. The areas under the ROC curves were large (0.81 at baseline and 0.93 at follow-up). The same BDI-21 cut-off point is suitable for screening major depression among outpatients in any phase of the disease.