A short account is given of the physical processus which can explain the presence of turbulent diffusion mixing (TDM) in the radiatively stable layers of rotating stars. The difference between full mixing and TDM is explained. In the case of the Sun, the excess of 3 He carried to the center of the Sun explains the efficiency of TDM in decreasing the central temperature and thereafter the small flux of Boron neutrinos. Other consequences of TDM are described, concerning (1) the relation between the present abundance of 3 He in the galaxy and the primordial abundance, (2) the abundance of Lithium in main sequence stars, and (3) the possibility of using the solar sismology as a test of the effect of TDM on the μ‐gradient.