Some studies have indicated that the capacity of self-assessment of affective state is more compromised during mania than during depression. In the present study, we investigated whether the reliability of self-assessment in bipolar disorder varies as a function of actual affective state (i.e., euthymia, mania, or depression). Sixty-five patients with a diagnosis of type I and type II bipolar disorder were evaluated with regard to the occurrence of an affective syndrome using the Clinical Global Impressions Scale for use in bipolar illness, the Positive and Negative Syndrome Scale, and the Global Assessment of Functioning scale. In parallel, we applied the Analog Visual Mood Scale, a self-assessment tool to evaluate mood changes. The same individual prospectively completed the self-assessment scale in different affective states. During depression, the patients' evaluation was significantly different from when they were in manic or euthymic mood states. However, when in mania, the patients evaluated their mood state similarly to when they were euthymic. The bipolar patients in mania but not in depression did not reliably evaluate themselves with regard to their affective state.