Vulnerability and risk assessment can be evaluated in a deterministic or a probabilistic way and this paper makes a comparison between the two approaches. A 2-D reinforced concrete frame, design according to the Romanian norm, was studied. Starting from the capacity curve obtained with a static non-linear analysis, fragility curves were ploted and an average damage index for the performance point of the structure was calculated. In the probabilistic approach the influence of uncertainties in the damage states thresholds is investigated on fragility and vulnerability curves. The obtained results for two coefficients of variation of the damage states thresholds simulated as random variables, meaning 10% and 20%, are also compared. The used procedures are based on the capacity spectrum method and on Monte Carlo simulations.