Brookfield Zoo, Zoo in Brookfield, Illinois, United States

Brookfield Zoo Chicago is a zoo in Brookfield, Illinois, covering 216 acres (87 hectares) and holding about 511 species. It is owned by the Forest Preserve District of Cook County and managed by the Chicago Zoological Society. Its exhibits are grouped by ecosystem, from Tropic World's indoor rainforest to Great Bear Wilderness, and its first building, the 1934 reptile house, now serves as a conservation center.

Edith Rockefeller McCormick donated land to the Cook County Forest Preserve District in 1919, and the district added 98 acres; the Chicago Zoological Society was established in 1921. Construction began in 1926 after a zoo tax was approved and slowed during the Great Depression. The zoo opened on July 1, 1934, using moats and ditches instead of cages, and drew over one million visitors by the end of September that year.

The zoo's name comes from its site in Brookfield, Illinois, not from a person; it was known simply as Brookfield Zoo until 2024, when it became Brookfield Zoo Chicago. The Roosevelt Fountain, added in the 1950s, is named for President Theodore Roosevelt. A 1996 incident made Binti Jua, a western lowland gorilla, known worldwide after she tended a boy who fell into her enclosure.

The site opens daily from 10 in the morning, and visitors should plan at least three hours to see the main areas. Pathways are paved and suitable for strollers or wheelchairs, and there are several covered areas for rainy weather.

The grounds hold official status as an accredited arboretum, preserving hundreds of rare tree species alongside animal enclosures. Some trees have stood since opening day and now form shaded avenues between exhibits.