Abstract: An indwelling injector needle assembly having wings includes a cannula or needle body, a hub supporting a proximal end of the needle body, a tube in fluid communication with the needle body, a cylindrical holder having a distal end from which the wings protrude, and a latching mechanism. The hub can slide along an inner periphery of the holder between a first position near the distal end of the holder and a second position near a proximal end of the holder. The latching mechanism is formed in and disposed between the hub and the holder so that the hub is inhibited from moving from the first position toward the second position, and vice versa. The needle edge can be retracted within the holder while its wings remain fixed to a patient's skin.