Study of the fatigue endurance and mechanical strength of solid solutions of the PZT–PZN–PMN system, modified with Ba and Sr, corresponding to the formula (Pb1−α1−α2Srα1Baα1) [TixZry〈(Nb2/3Zn1/3) (Nb2/3Mg1/3)〉1−x−y]O₃, with α1 = 0.02 ÷ 0.12; Δα1 = 0.02, α2 = 0.0036 ÷ 0.073; x= 0.385 ÷ 0.430, y= 0.402 ÷ 0.447 is presented. It is shown that the evolution of the polarization characteristics with an increase in the number of repolarization cycles, n, is characterized by two sections: slow fatigue and logarithmic evolution. It was found that an increase in the strontium content shifts the beginning of the logarithmic stage towards to the large n. It is shown that an increase in the average grain size decreases the mechanical strength. A conclusion is made about the expediency of using the obtained data in the development of devices operating in power modes.Study of the fatigue endurance and mechanical strength of solid solutions of the PZT–PZN–PMN system, modified with Ba and Sr, corresponding to the formula (Pb1−α1−α2Srα1Baα1) [TixZry〈(Nb2/3Zn1/3) (Nb2/3Mg1/3)〉1−x−y]O₃, with α1 = 0.02 ÷ 0.12; Δα1 = 0.02, α2 = 0.0036 ÷ 0.073; x= 0.385 ÷ 0.430, y= 0.402 ÷ 0.447 is presented. It is shown that the evolution of the polarization characteristics with an increase in the number of repolarization cycles, n, is characterized by two sections: slow fatigue and logarithmic evolution. It was found that an increase in the strontium content shifts the beginning of the logarithmic stage towards to the large n. It is shown that an increase in the average grain size decreases the mechanical strength. A conclusion is made about the expediency of using the obtained data in the development of devices operating in power modes.