Subjects in the study were 22 patients suffering from bipolar affective disorder and receiving prophylactic lithium treatment for 2 to 19 years, with a good effect. 31 episodes of the treatment discontinuation were noted. No "withdrawal symptoms" resulting from discontinuation of medication were noted. The risk of relapse due to the effective lithium treatment discontinuation is rather high, since 48% of the patients relapse during the subsequent month. A two-year remission was found in 25% of the subjects only. In the majority of the relapsed patients normalization of mood was attained by resumption of the lithium treatment. Incidence of lithium resistance due to discontinuation of treatment with this drug requires further study.