summary Several instruments are available for screening on mood disorders (depression and bipolar disorder) and for measuring their severity. During the treatment of unipolar depressions it is advisable to apply on a regular basis a severity scale such as the Inventory of Depressive Symptoms (IDS) which covers a wide range of depressive symptoms. Possible alternative instruments are the Hamilton Rating Scale for Depression (HRSD), the Montgomery Åsberg Depression Rating Scale (MADRS) or the Beck Depression Inventory II (BDI-II). When patients have a bipolar disorder it is advisable to follow the course of their disorder prospectively using the Life Chart Method (LMC).