The Mental Health Inventory (MHI)-5 is an attractive, brief screening questionnaire for depression and anxiety disorders. It has been suggested that the three questions on depression (MHI-d) may be as good as the full MHI-5 in assessing depressive disorders. We examined the validity of the MHI-d and the MHI-a (the remaining two items on anxiety) in a large population-based sample of 7076 adults in the Netherlands. We also examined the validity of the MHI in assessing specific anxiety disorders. The presence of depressive and anxiety disorders in the past month was assessed with the Composite International Diagnostic Interview (CIDI), computerized version 1.1. ROC analyses indicated no significant difference between the MHI-5 (area under the curve of 0.93) and the MHI-d (area under the curve of 0.91) in detecting major depression and dysthymia. There was no difference either between the MHI-5 (area under the curve of 0.73) and the MHI-a (area under the curve 0.73) in detecting anxiety disorders. Both the MHI-5 and the MHI-a also seem to be adequate as a screener for some anxiety disorders (generalized anxiety disorder; panic disorder; obsessive-compulsive disorder), but not others, especially phobias (agoraphobia; social phobia; simple phobia).