A safety blood collection device including holder housing adapted to maintain a needle cannula with a puncture tip extending from a forward end thereof and to receive a sample collection tube through a rearward end thereof. A retainer coacts with the holder housing to maintain the needle in a first position with the puncture tip of the needle extending from the forward end of the holder housing. The retainer is adapted for activation so as to release the needle from this first position, thereby permitting the needle to move based on the force of gravity and the weight of the needle to a second position in which the puncture tip of the needle cannula is contained within the interior chamber of the holder housing. As such, upright placement of the holder housing upon activation of the retainer will permit the needle to drop within the holder housing, thereby containing the needle cannula therein as a self-contained assembly.