Oud-Ade is a town in the Dutch province of South Holland. It is a part of the municipality of Alkemade, and lies about 7 km east of Leiden.
In 2001, the town of Oud-Ade had 336 inhabitants. The built-up area of the town was 0.04 km², and contained 119 residences. The wider statistical district "Oud-Ade and Zevenhuizen" has a population of around 610.