Abstract. We survey the known results and open questions related to the Lehmer Problem. We start by recalling the "classical" conjecture : the existence of a lower bound for the height of an algebraic number (not a root of unity) of the form h(α) ≥ and the generalizations to higher dimension. We discuss afterwards, the "relative" versions of these problems, that is, replacing de degree of α over Q by the degree over Q ab . We give the most recent results on these questions and we discuss briefly an application of the latest to the Pink-Zilber conjecture.