The aim of this work was to determine the high temperature compression behavior of the solid phase found in a semi-solid 6061 alloy by using an original procedure. A drained compressive test has been carried out to drain the majority of the liquid from the semi-solid alloy and obtain a solid representative of the solid phase of the alloy within the solidification range. The drained compressive tests have shown that the behavior of the semi-solid state is viscoplastic and depends on the initial morphology of the solid skeleton and on the accumulated strain. Then, compressive tests at high temperature have been carried out on drained and non-drained 6061 alloy. Results show that: (1) both alloys exhibit a behavior governed by a hyperbolic sine rheological law, (2) the deformation at high temperature of the drained alloy differs from the deformation of the non-drained 6061 alloy.