Psychoeducation has an impact on patient co-operation during the treatment of bipolar affective disorder. Over a 2-year period, lithium levels were compared every 6 months in two groups of patients: psychoeducated (n=49) and uneducated (n=44). The study supported the hypothesis that the best treatment results are obtained by supporting standard pharmacotherapy with education about the disease and its treatment. Psychoeducated patients had higher and more stable lithium levels than the control group.