Abstract: A disposable self-capping needle which can be completely contained with its own sheath before and after injection takes place. The enclosing needle sheath has a protective rear seal and an openable front lid. By removing the seal a syringe can be connected to an internal needle plunger assembly to permit reciprocating needle motion within its sheath. Injection is accomplished by opening the sheath's front lid after which the needle may be completely withdrawn back into the sheath for safe disposal. Internal sheath guiding and holding grooves permit the needle's plunger assembly to reciprocate freely.