This study is focused on the reliability assessment of seismic action for two existing reinforced concrete chimneys from thermoelectric powerplants situated in Bucharest and Iasi (Romania). A brief presentation on the design procedures for RC chimneys is also given in this study. The numerical models derived for two RC chimneys considered the uncertainty in material properties, as well as the soil-structure interaction effects. Incremental dynamic analyses (IDA) using real ground motion recordings from three Vrancea intermediate-depth earthquakes were performed in order to evaluate the seismic fragility of the two chimneys. The analyses have shown that the annual failure probability due to earthquake action is larger for the chimney located at Bucharest. The locations of the plastic hinges are mainly concentrated in the middle and upper part of both RC chimneys, unlike the case of regular structures.