A needle retraction medical device including a hollow body (10) and a plunger (20). The hollow body (10) has a first end (11) provided with a needle mounting hub (13) and a plurality of releasable latches (15) holding the needle mounting hub (13) against spring (14) bias. The latches (15) are formed integrally with the hollow body (10) and project longitudinally inside the hollow body (10) from a proximal end at or adjacent the first end (11) of the hollow body (10) to a free end. A respective opening (35) is provided in the body (10) radially inwards of each of the latches (15). The plunger (20) has a forward end insertable into the body (10) from a second end thereof, a hollow interior and a closed rear end. The plunger front end is operable, upon insertion of the plunger (20) into the body (10), to deflect the latches (15) radially outwards and thereby release the needle mounting hub (13) from the latches (15) so that the hub (13) together with the needle mounted thereby retract under spring action into the hollow interior of the plunger (20). A respective opening (30) is also provided in the hollow body (10) radially outwards of at least some of the latches (15) so that each such latch (15) connects to the material of the body (10) only at each side of its proximal end.