A temperament is described as a temporally stable dimension, biologically determined. Several temperaments have been described (hyperthymic, depressive, cyclothymic, irritable and anxious) and could represent premorbid characteristics of an affective disorder. Some temperaments could thus correspond to chronic sub-affective states expressed as attenuated forms of mood disorder. Several studies suggest that a large proportion of bipolar patients have a hyperthymic or cyclothymic temperament. Moreover, temperaments seem to influence the clinical caracteristics of bipolar disorders. Future investigations will evaluate whether temperaments represent a predisposing factor, an attenuated form of bipolar disorders or a distinct entity.