This report is the result of a research program on creep-fatigue damage conducted under a Grant from PVRC on engineering materials such as 316 stainless steel.The main objective of the program is to analyze, evaluate and develop a model for creep-fatigue interaction under uniaxial and biaxial stress/strain cycling at elevated temperature.The biaxial loading was torsion coupled with axial loading with 30 minutes hold-time to generate the creep effect.Data was obtained from fatigue-creep tests conducted at 1150F (620C). Based on test data and in-depth macro-micro analysis, a model which accounts for uniaxial creep damage is developed on the basis of ductility-exhaustion concept.A comparison is made between the proposed ductility-exhaustion model and the time fraction rule.The proposed model shows a better and more comprehensive prediction capability than the time fraction rule and was able to distinguish whether the failure is by creep or by low cycle fatigue.