Disclosed is a reusable surgical instrument (1) with an articulated end-effector (3), such as a dissector, scissor or grasper, to enhance a surgeon's performance during various surgical procedures. The longitudinal axis of the instrument is defined by a shaft (2), comprising an internal structural element (2″) covered by an external tube (2′), which may be inserted through a surgical incision into the body of a patient, optionally through a trocar. The articulated end-effector (3) is mounted on the distal extremity of the shaft's internal structural element and comprises a plurality of links interconnected by a plurality of joints, whose movements are remotely actuated by the surgeon's hands. This remote actuation is accomplished via mechanical transmission (5, 6, 7), mainly composed of flexible elements, which are able to deliver motion from a set of actuation elements, placed at a proximal extremity of the shaft (2), to the instrument's articulated end-effector (3). The external tube (2′) can be easily and individually detached from the shaft (2) after each procedure, so that the instrument (1) can be more effectively cleaned and sterilized.