A method for reducing the leakage of an organic working fluid operating within a turbine (10) of an Organic Rankine Cycle system, the method comprising the injection of a fluid flow rate (Q) into a volume (I) at a static pressure lower than the total pressure (P1) upstream of the turbine and located near of at least one labyrinth seal (L1, L11) of at least one stage of the turbine (10), said fluid flow rate (Q) having an initial exergetic content lower than the initial exergetic content of the organic working fluid located inside the turbine and flowing through said labyrinth seal (L1, L11).