We examine how the transparency of the European Central Bank´s monetary policy affects the amount of trust that the citizens of the European Union have in this institution. We use nearly half a million individual responses from the European Commission´s Eurobarometer survey from 2000-2011 and estimate probit regressions with sample selection. We find that transparency exerts a non-linear effect on trust. Transparency increases trust, but only up to a certain point; too much transparency harms trust. This result is robust to controlling for a number of macroeconomic conditions, financial stability transparency measures, and economic and socio-demographic characteristics of respondents, including examining respondents in European Union countries that do not use the euro and addressing clustering issues.