Oak Brook is a village in DuPage and Cook Counties, in Illinois. The population was 8,702 at the 2000 census. A suburb of Chicago, it is the headquarters of McDonald's.

As of the census of 2000, there were 8,702 people, 3,124 households, and 2,589 families residing in the village. The population density was 1,066.4 people per square mile (411.7/km²). There were 3,258 housing units at an average density of 399.2/sq mi (154.2/km²). The racial makeup of the village was 76.60% White, 1.37% African American, 20.11% Asian, 0.01% Pacific Islander, 0.22% from other races, and 1.69% from two or more races. Hispanic or Latino of any race were 2.39% of the population.

The median income for a household in the village was $146,537, and the median income for a family was $169,718. Males had a median income of $100,000+ versus $40,128 for females. The per capita income for the village was $76,668. About 1.4% of families and 2.1% of the population were below the poverty line, including 4.7% of those under age 18 and 0.4% of those age 65 or over.