Abstract: The invention relates to a safety valve for oil wells, able to permit artificial output operation by injection of a fluid under pressure. This valve comprises a movable closing flap (11), a tubular internal slide (9), a spring (10) for returning said slide to its upper position, a hydraulic system for displacing said slide downwardly due to pressure of a control fluid, an internal tube (300) for passage of injected fluid, fixed to the slide (9), a lower connecting sleeve of a series of lower tubes (Ti) for the passage of injected fluid, able to be connected with the internal tube (300) when the tube is in the lower position, an upper connecting sleeve (309) of a series of upper tubes for the passage of injected fluid, in which may slide in a sealed manner the internal tube, a system for anchoring the valve in a receiving sleeve (1) comprising a hydraulically actuated mechanical system controlled by the control fluid, and seals (15, 16) at the contact of the receiving sleeve (1).