Drought is a multiform constraint expressing at different plant organisation levels. It is recognised as the first factor limiting the agriculture production in the world. The Sahel subtropical regions were the most exposed to the devasting effects of the recent climate change. A state of knowledge referring to the plant responses to drought is a fundamental initial step to any program of selection. This review concerns more particularly groundnut (Arachis hypogaea L.), which is a very common legume in the Sahel areas. Critical evaluations of traits as relevant selection criteria for a breeding program aiming at improving yield and yield stability under drought constraint were made. The genetic specificities of the species are exposed in the first part. Then a detailed description of the grain-legume traits related to drought adaptation is presented. The review was widened to other plants for the molecular responses to water deficit, supposed to be more general. Finally, the last part supplied an updated synthesis of the recent advances in biotechnology on groundnut with special focus on drought tolerance.