Based on intraday high-frequency data, this paper investigates the effect of sterilized interventions on the Slovak koruna/euro exchange rate for different time windows during a period that coincides with Slovakia’s preparation for EU accession and euro adoption. Results confirm a significant relationship between intervention and exchange rate change. The maximum effect of intervention is reflected in the exchange rate change within a couple of hours, and the effect over longer time windows weakens only gradually. The initial impact of sale interventions is stronger than that of purchase interventions. © 2017, Association for Comparative Economic Studies.