The elastic response of a metastable β titanium alloy, Ti-25Nb-3Zr-3Mo-2Sn, is characterised. The effects of processing and heat treatment on phase composition and mechanical behaviour are reported. The alloy exhibits pseudoelastic behaviour which is related to the reversible formation of the stress induced α" phase. The solution treated condition displays the greatest pseudoelasticity and the hot rolled condition the least. Tensile deformation reduces the modulus of the alloy. This is due to increases in the relative proportions of the low modulus α" phase.