Background: Temperament refers to trait expressions, resulting from a genetic-constitutional background that sustain energy levels and mood state and represent a main variable accounting for the reactivity in facing an external trigger. The different models of the relationships and interactions between personality/temperament and illness in affective disorders are discussed. The role of affective temperaments in psycho(pato)logy is double, both representing the earliest subclinical phenotypes in continuum with and preliminary for developing mood disorders, and a fundamental state for the expression of personality.