A linear actuator, in particular telescopic legs for height-adjustable tables, and comprising an outer profile (18), a spindle (7) mounted at an upper end of the outer profile, a transmission (8) connecting the spindle (7) with a reversible electric motor, a spindle nut (11) secured against rotation on the spindle (7), an intermediate profile (10) mounted with its one end on the spindle nut (11), a guide at a lower end of the outer profile (18) for the intermediate profile (10), a cord element (12, 20; 26) secured at the lower end of the outer profile (18) and connected via a guide with an inner profile (14), such that this together with the intermediate profile (10) is telescopically pushed out of and into the outer profile (18) by the rotation of the spindle. When the inner profile (14) is secured against rotation on the intermediate profile (10), and the rotational securing of the spindle nut (11) is constituted by longitudinal guides in the outer profile (18), then an actuator is achieved which per se is secured against rotation, i.e., when applied in telescopic legs, there is no need to have a rotational protection via the leg. In general, the structure is slender and may thereby be used in thin telescopic table legs.