Medical device with resiliently retracting safety needle

A medical device for percutaneous or venous access for administering a fluid to a patient or sampling from one, comprising a tubular body from which there projects a cannula supported at a distal end of a cannula holder, a proximal end of said cannula holder being attached to a tube in which said fluid can circulate, said cannula holder being able to move within said body of the device under the force of a resilient thrust element, a stop member of one piece with said body and able to impede said movement of the cannula holder being provided and activating means being provided to allow such movement associated with body of the device acting together with activating counter-means of one piece with said cannula holder, wherein said cannula holder has a yielding part between its said distal end and said proximal end, said yielding part allowing said cannula holder to flex within the body of the device when said activating means are activated so as to separate said cannula holder from said stop member to allow axial movement of the cannula holder in the body of the device and disappearing retraction of the cannula needle into this body.