Experiments were conducted to measure the extent of slippage occurring when thin disks are processed by high-pressure torsion. Separate tests were conducted on aluminum, copper and iron. The results show the extent of slippage varies between these three materials such that there is very little slippage in aluminum, slightly more slippage in copper and significant slippage when using iron. For all materials, the extent of slippage increases at both faster rotational speeds and lower imposed pressures.