Leersum is a town in the Dutch province of Utrecht. It is a part of the municipality of Utrechtse Heuvelrug, and lies about 7 km east of Doorn and 9 km west of Veenendaal.
In 2001, the town of Leersum had 6013 inhabitants. The built-up area of the town was 1.44 km², and contained 2465 residences.
Until 2006, there was a separate municipality Leersum, covering both the village of Leersum and Darthuizen.
In June 2021, Leersum was hit by a downburst. Many cars and homes were heavily damaged by falling trees. As a result, the forests around Leersum have been closed. Staatsbosbeheer, the Dutch state forest administration, estimates that damaged sections of forest will not be reopened to the general public before the end of the year 2021.