Our contribution is focused on the definition and transformation of bodies by present-time scientific and technological practices. Scientific and technological interventions, modify, repair, amplify or restrain human bodies. Our text follows accordingly interventions and manipulations which affect sick and healthy bodies, handicapped bodies, reproducing bodies and bodies at work. It also traces recent scientific, medical, industrial and commercial uses of body parts (organs and body fluids, cells and tissues, gametes, macromolecules, DNA) and the multiple lives of digitalized and virtual bodies. It is especially interested in promise and limits of scientific and technological interventions and in the ways such interventions alter fundamental classificatory categories -- sex, gender, race, or ethnicity -- and redraw the boundary between "nature" and "culture.