In the scientific literature, a significant number of non-linear procedures are proposed in order to evaluate the seismic vulnerability of a building. In this work, and in the context of the Risk-UE methodology, a complete comparison of six representative nonlinear procedures, applied to an unreinforced building, has been performed. The incremental dynamic analysis has been considered in order to provide a reference for comparisons. Additionally, the evaluation of the applicability and reliability of the nonlinear static procedures has been performed and, some simple modifications, oriented to improve their use, have been proposed. The seismic demand has been conveniently defined applying the conditional spectrum approach procedure. Two different methodologies were used in order to define the fragility curves. Accordingly, a complete comparison of the calculated damage indices and the damage curves, corresponding to the different considered peak ground acceleration values, has been undertaken. The comparison results let know that the damage curves obtained by performing the non-linear procedures and by applying the Risk-UE methodology tend to overestimate the damage corresponding to low values of the PGA while the damage related to higher values of the PGA is underestimated.