We have studied the compressibility and stability of different β-titanium alloys at high pressure, including binary Ti-Mo, Ti-24Nb-4Zr-8Sn (Ti2448) and Ti-36Nb-2Ta-0.3O (gum metal). We observed stability of the β phase in these alloys to 40 GPa, well into the ω phase region in the P-T diagram of pure titanium. Gum metal was pressurised above 70 GPa and forms a phase with a crystal structure similar to the η phase of pure Ti. The bulk moduli determined for the different alloys range from 97 ± 3 GPa (Ti2448) to 124 ± 6 GPa (Ti-16.8Mo-0.13O).