A quantitative determination of the contributions of the triply negatively charged Ga vacancies (V3-Ga) and of the doubly positively charged Ga self-interstitials (I2+Ga) to the Ga self-diffusion coefficient in GaAs has been carried out. Under thermal equilibrium and intrinsic conditions, the V3-Ga contribution is characterized by an activation enthalpy of 6 eV for As-rich crystals and of 7.52 eV for Ga-rich crystals, while the I2+Ga contribution is characterized by an activation enthalpy of 4.89 eV for As-rich crystals and of 3.37 eV for Ga-rich crystals.