The thermal fatigue (TF) behaviour of two single crystal nickel-based super-alloys, SRR99 and CMSX-4, is reported. Single edge wedge specimens are rapidly heated by induction heating of the wedge tip to a maximum temperature between 1000‡C and 1175‡C and cooled to 200‡C by forced air. A constant cycle period is employed for all experiments. The strain distribution along the edge of the TF specimens is measured. Changing the induction frequency leads to different strain ranges. CMSX-4 shows crack initiation always on cast microporosities. SRR99 presents an additional oxidation/spalling/re-oxidation mechanism under low strain loading. An “integrated approach” combining TF and TMF (thermo-mechanical fatigue) is proposed. The applied TMF temperature-strain cycle is deduced from the measured TF-cycle. Under this new temperature-strain cycle the crack initiation life and the total life in TMF for SRR99 are compared with the TF results.