A needle stick prevention device for a medical infusion set including a base, the base having a column extending proximally from the base, and a head extending from the column forming an undercut between the base and the head, the needle stick prevention device comprising: a needle shield for selectively covering a distal end of a needle, the needle shield being proximal to the base and including an outer wall with a passageway communicating with a proximal end and a distal end, wherein the proximal end includes a proximal opening and the distal end includes a transverse opening communicating with a distal opening extending through the distal end; a needle hub movably received within the passageway of the needle shield, the needle hub including: a proximal end; a distal end; and a needle fixedly connected to the distal end of the needle hub; characterized by an actuation button including an upper latch having a first key hole with a locking portion and an unlocking portion and a lower latch having a second key hole with a locking portion and an unlocking portion movably received in the transverse opening of the needle shield to selectively engage the needle shield, the needle hub and the medical infusion set; and a spring disposed between the needle hub and actuation button, wherein the needle stick prevention device is configured so that in a first state, the upper latch of the actuation button is received in the recess of the needle hub, the hub flange is engaged with an undersurface of the upper latch, and the lower latch of the actuation button is received in the undercut formed between the column of the infusion set base and head, so that the actuation button engages the needle hub and the base, the spring is held in a compressed state between the needle hub and actuation button, and the medical infusion set is releasably locked with the actuation button, and in a second state, after the actuation button is actuated, the actuation button releases the needle hub and the infusion set base so that the infusion set base may be removed from the needle shield and actuation button by passing the head through the unlocking portion of the lower latch, the needle stick prevention device is removable from the medical infusion set, the spring is released, and the needle hub is movable relative to the needle shield. a needle shield for selectively covering a distal end of a needle, the needle shield being proximal to the base and including an outer wall with a passageway communicating with a proximal end and a distal end, wherein the proximal end includes a proximal opening and the distal end includes a transverse opening communicating with a distal opening extending through the distal end; a needle hub movably received within the passageway of the needle shield, the needle hub including: a proximal end; a distal end; and a needle fixedly connected to the distal end of the needle hub; characterized by a proximal end; a distal end; and a needle fixedly connected to the distal end of the needle hub; characterized by an actuation button including an upper latch having a first key hole with a locking portion and an unlocking portion and a lower latch having a second key hole with a locking portion and an unlocking portion movably received in the transverse opening of the needle shield to selectively engage the needle shield, the needle hub and the medical infusion set; and a spring disposed between the needle hub and actuation button, wherein the needle stick prevention device is configured so that in a first state, the upper latch of the actuation button is received in the recess of the needle hub, the hub flange is engaged with an undersurface of the upper latch, and the lower latch of the actuation button is received in the undercut formed between the column of the infusion set base and head, so that the actuation button engages the needle hub and the base, the spring is held in a compressed state between the needle hub and actuation button, and the medical infusion set is releasably locked with the actuation button, and in a second state, after the actuation button is actuated, the actuation button releases the needle hub and the infusion set base so that the infusion set base may be removed from the needle shield and actuation button by passing the head through the unlocking portion of the lower latch, the needle stick prevention device is removable from the medical infusion set, the spring is released, and the needle hub is movable relative to the needle shield.