1. Under the present conditions of induction heating for surface quenching, controlled by the parameters of the generator, the temperature-time curves in the temperature range of phase transformation may be convex, concave, or both. A constant heating rate during phase transformation is seldom found in practice. 2. The rate of heating and the shape of the temperature-time curve change when a piece of equipment (generator, capacitors, high-frequency transformer) is replaced, although the working conditions of the generators are kept constant. For reproducible results in surface quenching one must reproduce not only the final temperature and the average rate of heating during phase transformation but also the shape of the temperature-time curve. 3. The new method of control ensures reproducibility of induction heating for a given machine part and for a given inductor, provided the tuning and the elements of the equipment (generator, capacitor, high-frequency transformer) remain the same. These methods are called individual methods of control. 4. Semi-universal methods of control of induction heating are based on one-step or several-step stabilization of the electric parameters of the inductor. These methods ensure complete reproducibility of heat-treatment conditions and of the results of surface quenching for a given size of the conductor and the machine part with any induction equipment, provided the current has the same frequency and the generator has sufficient power. 5. Universal methods of controlling induction heating are based on the use of rectilinear temperature-time curves with a constant rate of heating at phase transformation temperatures, or isothermal heating at the final temperature. These methods ensure complete reproducibility of heat-treatment conditions and of the results of surface quenching on any inductor and for any machine part, provided the frequency of the current is the same and the generator has sufficient power.