In this paper, using the models from the economic literature, the authors study the credibility level of National Bank of Romania (NRB) during the time span Mars 2007 – Mars 2008. We will use three types of credibility indexes - two from the economic literature and one proposed by the authors. Also, we will emphasize the impact of unpredictable shocks - the natural calamities (drought) which affected the aggregate supply in the summer of 2007 and the depreciation of RON against the euro - on the NBR credibility.