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Low cycle fatigue tests on nickel base superalloy GH4049 were conducted at various temperatures from 500 to 850 degrees C in laboratory air. The strain-life and cyclic stress-strain data were analyzed and the change in fatigue life behavior and fatigue parameters with increasing temperature was discussed. At low and intermediate total strain amplitudes, the fatigue life was found to decrease with increasing temperatures. The fracture surface of the fatigue specimens was studied using scanning electron microscopy. It was found that fatigue crack initiation is transgranular, however, fatigue crack growth exhibits a strong dependence on temperature. The cyclic deformation process, creep and oxidation are thought to be the main causes of fatigue life reduction and intergranular cracking. (C) 1999 Elsevier Science Ltd. All rights reserved.