A minimally invasive surgical instrument having an elongate stem extending between a proximal end which in use is located externally of an operating space and a distal end which in use is located within an operating space. At least a portion of the stem is malleable to facilitate manipulation of the stem in the operating space and then to maintain the stem in the manipulated position and/or orientation within the operating space. The instrument has an end effector at the distal end of the stem, the end effector having a proximal main body and distal operating means, such as graspers or cutters. The instrument has at least one joint for independent movement of the end effector main body in at least one direction relative to the distal end of the stem for enhanced degrees of freedom of the instrument.