The electrical conductance of single crystals of olivine has been measured during creep in the temperature range 1610--1725 K, under controlled oxygen fugacity and under uniaxial stresses of 60--140 MPa. During deformation at a constant uniaxial load, the measured conductance increases continuously with time. During high-temperature annealing in the absence of load, the conductance of deformed crystals remains constant with time. The total change of conductance resulting from deformation is found to be strongly dependent on the total strain. Comparison between this conductance change and that expected from measured geometrical shape changes of the specimens indicates that the latter is the dominant contributor to the total change in conductance. The results presented indicate that the generation and movement of dislocations and other defects associated with plastic deformation do not significantly contribute to the electrical conductivity of olivine. In addition, the results suggest that the electrical conductivity of the upper mantle will not be affected by the lateral variations in tectonic stresses.