The dislocation relaxation of MgO and Al2O3crystals was studied by means of anelastic measurements. The experimental data are analyzed according to the theory of Seeger, Donth, and Pfaff. It is shown that the ratio of Peierls force to shear modulus is about 2×10−5for MgO and possibly also for Al2O3. Comparison of the dislocation relaxation phenomena of oxides and metals indicates, rather surprisingly, that the ratio of Peierls force to shear modulus in oxides is about an order of magnitude smaller than that in fcc metals.