The paper deals with results of special fatigue life tests. Random processes of different power spectral densities loaded tube specimens made of a mild carbon steel ČSN 411523.1 (11523.1), notched by a perpendicular hole. It has been found that fatigue lives build similar S-N curves like by harmonic loadings, when the standard deviation s^d of peaks of an effective damaging stress and number of loading blocks Nb are used instead of amplitudes oa, and number of cycles Na, respectively. S-N curves of unaxial and multiaxial loading are compared in the paper.