A safety device for shielding the sharp tip of a medical needle has a needle mount which either directly supports a medical needle, or indirectly supports the needle for instance where the needle is provided as a part of a syringe. A sleeve is carried directly or indirectly on the needle mount and is slidably movable to a needle shielding position where the sleeve surrounds the needle sharp tip. A spring including forwardly projecting spring blades when sufficiently loaded acts on an internal conical surface of the sleeve to drive the sleeve to its shielding position and a locking mechanism then locks the sleeve in that position. A camming mechanism serves to load the spring blades in the course of the use of the safety device such that thereafter the interaction of the blades with the conical surface urges the sleeve to its shielding position, the camming mechanism being activated by movement of the sleeve to expose the needle for use.
