Oud-Zuilen is a town in the Dutch province of Utrecht. It is a part of the municipality of Stichtse Vecht, and lies about 4 km northwest of Utrecht. It is in an area called the "Vechtstreek".
In 2001, the town of Oud-Zuilen had 224 inhabitants. The built-up area of the town was 0.069 km², and contained 84 residences.
The statistical area "Oud-Zuilen", which also can include the peripheral parts of the village, as well as the surrounding countryside, has a population of around 1350.