Maartensdijk is a town in the Dutch province of Utrecht. It is a part of the municipality of De Bilt, and lies about 4 km north of Bilthoven. In 2001, the town of Maartensdijk had 4395 inhabitants. The built-up area of the town was 0.84 km², and contained 1744 residences. Including the surrounding countryside, the statistical area "Maartensdijk" has a population of 5010.