A butterfly needle (100) for venipuncture comprises a body (1) with two protruding flexible tongues (2) that can be bent by manual gripping by the user from a diverging position to a converging position, and a needle (9) mounted axially in the fore end of a needle-carrier (3) which a tail (8) protruding rearward from the body (1) to couple with the connection of a flexible tube destined to be connected to a syringe or a bottle. The needle-carrier (3) is mounted axially slidable in the body (1) to pass from a forward position of use wherein the needle (9) protrudes forward from the body (1) to perform the injection to a retracted position of safety wherein the needle (9) is protected inside the body (1), there being provided guide means (13, 33) able to guide the axial movement of the needle-carrier (3) inside the body (1) and end-of-stroke and locking means (18, 17, 36) able to lock the needle-carrier is said advanced position and in said retracted position.