A blood sampling device 10 having body 12 having an opening 20 therein for receiving a retractable needle holder 14. The device also has a biasing member 25 for biasing the needle holder to a deployed position, a retraction mechanism 26, a latching mechanism 28 and a releasing mechanism (30, Fig. 2). The body also includes one or more slots 40 which receive a portion of the retractor mechanism, the slots having closed end 42 and openable end 44, the openable end movable between a closed position which prevents the retraction member being inserted and removed and an open position in which the portion of the retractor mechanism may be inserted or removed. The body may have top and bottom portions (12t and 12b, Fig. 2) and side portions (12e and 12f, Fig. 2) with two slots 40a and 40b on each side opposite each other. The top and bottom portions being linked at the closed ends of the slots by joining potion (50, Fig. 2) and may pivot about the joining portion to open the openable ends of the slots.
