Fatigue behaviour of ultrafine-grained copper of purity 99.9 % produced by ECAP technique was studied in a broad region of stress amplitudes. Fatigue strength is by a factor of about 2 higher than that of conventional-grain-size copper in the broad region of fatigue lives from 6x103 to 2x1010 cycles. The grain structure is stable and undergoes only very marginal changes during cycling. Fatigue slip markings on specimen surface follow the trace of the shear plane of the last ECAP pass. Fatigue notch sensitivity is also higher than that of conventional-grain-size copper, but not dramatically. The cyclic stress-strain curve of studied copper is temperature insensitive, while its S-N curve is temperature dependent.