Transportation systems and bridges must continue to be used safely to maintain society's development and economic growth. For this reason, the structural capacity of these bridges should be determined more realistically and accurately. Reliability analysis determines the probability of failure of a bridge in a statistical way. Existing specifications used a semi-probabilistic approach to calculate the reliability of the bridge and determined a threshold to sustain the safety of the bridge. The development in civil engineering and the more information about the transportation system's material properties and loading conditions make the statistical models more accurate. The advance in technology also makes it possible to apply probabilistic reliability analysis of the bridge. These studies use Monte-Carlo simulation and generate a probabilistic reliability analysis of selected RC box girder bridges. Material properties of the bridge were determined by the experimental data, and normal and log-normal distributions were used to represent the concrete and reinforcement. Normal distribution was used to simulated both dead and live load on the bridge. Bridge collapse loads were determined by the limit analysis theory and simulated. Finally, reliability of the bridge was determined. The results and methodology were discussed in detail.