An Illinois Tollway oasis is a type of commercialized rest area sited over Interstate Highways that are part of the Illinois Tollway system in northern Illinois, United States. The four oases offer food and gasoline vendors and are found in the Chicago Metropolitan Area, DeKalb, and Belvidere. Although the oases date back to the original tollway construction in 1958, they were redeveloped in 2003–2005 by Wilton Partners, a private developer. The redevelopment of the oases has been the focal point of alleged political corruption. The four oases are administered by a court-appointed manager following default of Wilton Partners.

The Illinois State Toll Highway Authority (ISTHA) is an administrative agency of the U.S. state of Illinois charged with building, operating, and maintaining toll roads in the state. The roads, as well as the authority itself, are sometimes referred to as the Illinois Tollway. The system opened in 1958 in the Chicago area, and has subsequently expanded to include the eastern and central sections of Interstate 88 (I-88) extending into the northwestern part of the state. Beginning in 2005, the system was reconstructed to include more lanes and open road tolling, the latter of which uses I-Pass transponders to collect revenue as vehicles pass antennas at toll plazas or designated entrance or exit ramps. As of 2017, ISTHA maintains and operates 294 miles (473 km) of tollways in 12 counties in Northern Illinois.