Current elevated-temperature nuclear system design rules require consideration of the time to the onset of tertiary creep as one factor in the determination of design-allowable stress intensity limits. However, tertiary creep data are often scarce, and little work has been done in their analysis. Time to tertiary creep data may be analyzed by the same parametric techniques that were developed for treating rupture life data. Also, time to tertiary creep, t3, is expressed as a function of rupture life,tr by, , where A and β are material constants. Finally, comparisons between these two prediction methods show that they produce similar results.