A safety device for shielding a medical needle having a sharp tip, which device comprises: - a needle mount for directly or indirectly supporting a medical needle; - a needle shielding sleeve for surrounding a supported needle and arranged coaxially with the mount so that a force applied to the sleeve slides the sleeve relative to the mount from a needle shielding position towards a non-shielding position whereat at least the tip of the needle is exposed beyond the sleeve; - an abutment surface and a sliding surface provided on one of the sleeve and mount; and - a radially deformable resilient finger provided on the other of the sleeve and mount, and serving as a spring, the finger having an inner surface and a part in radial alignment with the abutment surface when the finger is undeformed to block movement of the sleeve from its needle shielding position; characterised in that there is: - a control member having an outer surface and arranged coaxially with the sleeve and mount and slidably displaceable from a set position with respect thereto; the arrangement of the control member being such that initial movement of the sleeve towards a non-shielding position slidably displaces the control member from said set position and causes relative movement between the finger and the control member, the inner surface of the finger riding up the outer surface of the control member to radially deform the finger and move said part thereof out of radial alignment with the abutment surface thereby to allow the sleeve to move to a non-shielding position and bring the inner surface of the finger into contact with the sliding surface, and continued movement of the sleeve slides the inner surface of the finger along the sliding surface to increase the radial deformation of the finger and store energy in the spring to urge the sleeve to a needle shielding position whereat the finger is undeformed and said part is in radial alignment with the abutment surface, thereby to block movement of the sleeve towards a non-shielding position consequent upon the displacement of the control member from the set position. - a needle mount for directly or indirectly supporting a medical needle; - a needle shielding sleeve for surrounding a supported needle and arranged coaxially with the mount so that a force applied to the sleeve slides the sleeve relative to the mount from a needle shielding position towards a non-shielding position whereat at least the tip of the needle is exposed beyond the sleeve; - an abutment surface and a sliding surface provided on one of the sleeve and mount; and - a radially deformable resilient finger provided on the other of the sleeve and mount, and serving as a spring, the finger having an inner surface and a part in radial alignment with the abutment surface when the finger is undeformed to block movement of the sleeve from its needle shielding position; - a control member having an outer surface and arranged coaxially with the sleeve and mount and slidably displaceable from a set position with respect thereto; the arrangement of the control member being such that initial movement of the sleeve towards a non-shielding position slidably displaces the control member from said set position and causes relative movement between the finger and the control member, the inner surface of the finger riding up the outer surface of the control member to radially deform the finger and move said part thereof out of radial alignment with the abutment surface thereby to allow the sleeve to move to a non-shielding position and bring the inner surface of the finger into contact with the sliding surface, and continued movement of the sleeve slides the inner surface of the finger along the sliding surface to increase the radial deformation of the finger and store energy in the spring to urge the sleeve to a needle shielding position whereat the finger is undeformed and said part is in radial alignment with the abutment surface, thereby to block movement of the sleeve towards a non-shielding position consequent upon the displacement of the control member from the set position.