Beryllia beams were loaded at temperature in four-point bending to a deflection of 0.001 in. or 0.002 in. and the decrease in load necessary to maintain the deflection constant was measured as a function of time. The beryllia was fine-grained, in the range ∼ 1 to 7μm, and the porosity varied between 3 and 21%. The test conditions covered a temperature range of 850 to 1240°C, experiments took from 10 min to 8 h: the loads used produced initial maximum outer fibre stresses of the order 3000 to 6000 psi.