An experimental investigation into the asymptotic stage of the separation of the turbulized mixtures of two fluids with densities ratio n = 3 has been carried out. The turbulized mixtures resulted from Rayleigh–Taylor instability when the contact boundary between two fluids was moved under an acceleration. At a certain instant of time, the system changes from the gravitationally unstable mode to the gravitationally stable one by the way of changing of the acceleration sign. During the ampoule motion with the investigated fluids at the gravitationally stable mode, the depth of penetration of the heavy fluid into the light one was registered with the photographic method. The length of the ampoule way at the gravitationally stable mode has been fixed so that the final (asymptotic) stage of the separation could be registered. At the result of themeasurements, it has been determined the separation process at the asymptotic stage has the same dimensionless velocity asat the initial stage.