An extended model for the assessment of fatigue reliability of steel structures in the presence of residual stresses is developed. The model explicitly includes the uncertainties of the mean stress and residual stress in terms of the zeromean equivalent stress-range. It is assumed that the fatigue life of welded joints follows the Weibull distribution. Based on the numerical illustrations, it is shown that the probability of fatigue failure and the allowable stress-range for fatigue design could be significantly affected by the presence of residual stresses. This effect may be represented through the mean stress at the welded joints.