Methods Monthly affective symptom status ratings for 30 patients with BP-II were based on interviews conducted at 3- or 6-month intervals during 5 years of prospective follow-up. The clinical characteristics and number of shifts in symptom status and polarity were examined. Results In these 5 years our patients with BP-II were symptomatic 61.2% of all follow-up months: depressive symptoms (55.4% of months) dominated over hypomanic (13.4% of months) and mixed (7.3% of months) symptoms. Subsyndromal (minor) depressive and hypomanic syndromes were evaluated in 23% of months. With mixed syndromes together it is 30.3% of months! Conclusions We propose the introducing of INTERMEDIATE STATE (subsyndromal depression, mixed and hypomanic states) in course of bipolar affective disorders, with special importance of this new clinical concept for etiological research and more targeted pharmacotherapy. We think that the new name/diagnosis TRIPOLAR affective disorders (depressive, manic and intermediate states - subsyndromal depression, hypomanic and mixed states) is more adequate for the course of this chronic affective illness.