A general approach is suggested for the analysis of nonlinear resonance in control systems including an integral linear term and a nonlinear term with hysteresis. This approach uses a special property of nonlinear terms which is valid for many important classes of hysteresis operators. For systems with such hysteresis nonlinearities, we introduce a method to derive conditions for the existence of forced oscillations and (for systems with a parameter) of nonlinear resonance at infinity.