An analysis of zirconium tensile stress-strain data was made by the Crussard and Jaoul method and an analogous method based on the Swift equation ϵ_p = ϵ_po + cσ^m. Data from transverse and longitudinal specimens from 4 to 813 K were considered. Also investigated were the effects of a small 77 K prestrain on the 300 K deformation behavior, and the effect of composition on the deformation at an intermediate temperature (≅575 K). The two analyses revealed the same basic deformation stages in all specimens. Transverse and longitudinal specimens exhibited, in general, a different pattern of stages. At elevated temperatures (above 550 to 600 K) pure zirconium tends to exhibit single-stage behavior. Specimens in which kinking or twinning are significant factors showed multi-stage behavior. The basic pure zirconium stress-strain curve is one in which the stress-strain curve slope decreases rapidly with increasing stress.