The author examined the problem of interpolation and extrapolation of the characteristics of high-cycle fatigue resistance of creep-resisting metallic materials with an allowance made for the loading frequency and temperature. The temperature-frequency dependence is given by the product of the functions of the modified temperature-time dependence of long-term strength and the exponential dependence on loading frequency. The accuracy of application of these dependences in approximation of basic experimental data and the reliability of solving the problems of interpolation and extrapolation were evaluated by statistical methods. The solution of the problem was verified with an example of EI867 creep-resisting nickel alloy using experimental results obtained in the working temperature range 1073–1273 K, cyclic endurance tests of 104-108 cycles (1–1000 h), and loading frequencies of 3–200 Hz.