Abstract: A shape memory alloy actuation apparatus comprises a support structure (2) and a movable element (10). A helical bearing arrangement (20) supporting the movable element on the support structure guides helical movement of the movable element with respect to the support structure around a helical axis (H). At least one shape memory alloy actuator wire (60) is connected between the support structure and the movable element in, or at an acute angle to, a plane normal to the helical axis, so as to drive rotation of the movable element around the helical axis which the helical bearing arrangement converts into said helical movement.