Using the extended Hückel method and the methods based on thermochemical, thermodynamic, and electrophysical data, the energies of vacancy formation in A II VI , A III B V , and A IV B VI semiconductor crystals have been determined. A correlation of the obtained values with one another and with the literature experimental and ab initio theoretical data is established. This testifies to the adequacy of the applied methods and to a possibility of using them for the estimation of the defect concentration in semiconductors. K e y w o r d s: semiconductors, point defects, defect formation energy.