High-temperature creep-fatigue behavior of the Alloy 709 is investigated by performing strain-controlled creep-fatigue tests at 650 °C and 750 °C with tensile hold times of 0, 60, 600, 1,800 and 3,600 s at 1% strain range and strain rate of 2 × 10−3 s−1. Results revealed that creep-fatigue life at 650 °C fluctuates due to Dynamic Strain Aging (DSA) during hold periods. Linear damage summation (LDS) was employed to construct the creep-fatigue interaction diagram of the alloy at different loading conditions. An increased density of cracks and creep cavities is observed at 750 °C with less dislocation density compared to 650 °C.