Stress-strain curves and electrical resistance measurements were made on single crystals of 99.99+% pure aluminum pulled in tension at 4°K. The stress-strain data show that beyond the easy-glide region the stress-strain curves are linear with a slope that depends on crystal orientation. If the specimen is unloaded and aged at room temperature, a small upper yield point occurs on reloading at 78°K or 4°K. The resistance produced by deformation is the same in all crystallographic directions. It increases as the square of the resolved shearing stress. Annealing at 78°K produces a 10% drop in the strain-induced resistivity (which is still isotropic). Annealing at 300°K produces a 65% drop in the strain-induced resistivity (again isotropic).