Torsion tests to large strains (ϵ = 3–10) in the intermediate temperature range (0.2−0.6 T m where T m is the melting temperature in degrees absolute) have been performed on high purity aluminum. Steady-state was reached at all temperatures except for 0.2 T m . Between 0.29 and 0.48 T m ä the activation energy for steady-state creep ( Q ss ) was found to be equal to about 87 kj mole −1 which corresponds quiteclosely to the activation energy for dislocation pipe diffusion as measured by Volin, Lie and Balluffi using a void shrinkage analysis. The relation between stress, σ ss, and strain rate, ϵ ss , in steady-state has been analyzed using an effective diffusion coefficient, D eff , for creep data over the temperature range 0.21-0.93 T m . The D heff utilized is based on all published diffusion data, namely two different additive lattice self-diffusion coefficients and one dislocation pipe diffusion coefficient. Over 21 orders of magnitude in ϵ ss / D eff , the data fit the equation ϵ ss D eff = B[ sinh(α σ ss E )] n , where α B and n are constants and E is the dynamic unrelaxed average Young's modulus. This Garofalo-type hyperbolic-sine equation is therefore a good representation of the steady-state behavior of pure polycrystalline aluminum. The activation energy for transient deformation, Q trans , was found to be dependent upon the method of testing. Q trans was greater than Q ss when calculated from temperature-change tests but less than Q ss when calculated from constant temperature tensile tests.