Transformation superplasticity was studied in the alloys Zr-702 (>99.2% Zr) and Zr-705 (Zr-2.5%Nb) by deforming them under various stresses while cycling the temperature about their phase transformation range. Zr-702 has a narrow range of transformation, and exhibits transformation superplasticity typical of pure metals, where average strain-rate under thermal cycling is proportional to applied stress (average strain sensitivity of unity). Zr-705 has a wide range of transformation temperature, and also exhibits superplasticity when cycled from 100% alpha to 100% beta. Additionally, when cycling partially within the alpha-beta range, superplasticity is also observed, but at a lesser rate.