A blood collection assembly includes a needle cannula (32), a hub (40) mounted on the needle cannula, and a spring (100) biased pivoting shield (60) pivotably mounted to the hub and moveable about a pivot axis between a retracted position and a shielded position encompassing a distal end of the needle cannula. A needle holder (12) is mated at a first end with the hub, and is adapted for receiving a blood collection container such as an evacuated tube through the opposing end. A retaining member (80) is attached to the pivoting shield and is releasably engageable with the hub to maintain the pivoting shield in the retracted position against the spring bias. Insertion of a blood collection tube into the needle holder (12) causes the retaining member to release from engagement with the hub, thereby causing the pivoting shield (60) to move toward the shielded position due to the spring bias.
