It is well known that prior deformation (either monotonic or cyclic) affects the subsequent fatigue behavior of some metals and alloys. A study of this history dependence of cyclic deformation behavior is important, because in engineering application, components quite often experience varying loads and temperatures. Results reported so far indicate that the fatigue behavior of materials, with low/intermediate stacking fault energy, depends very much on the prior history of the sample whereas the behavior of the wavy slip mode materials is not so dependent. The authors chose for the present investigation, a nickel base superalloy, Nimonic PE16, strengthened by the precipitation of [gamma][prime] particles (Ni[sub 3]Al,Ti), having spherical morphology, low volume fraction and uniform distribution in the austenite matrix. This paper reports the results obtained on the effect on prior room temperature cyclic deformation on the elevated temperature fatigue behavior of this alloy, corresponding to two initial microstructural conditions. The results are interpreted in the light of the present understanding of the mechanism of fatigue deformation and the results of transmission electron microscopic (TEM) examination of fatigued samples.